Chouteau County, MT: risk-assessment baseline packet, release 2026-10

Summary

Plan status as of 2026-09-30: Approved, expires 2029-10-11. Plan: Central Montana Regional Hazard Mitigation Plan 2024 (FEMA plan 109563), approved 2024-10-12.

Since the plan was approved on 2024-10-12: no new federal declaration.

NOAA Storm Events records since that date: 82 records (data through 2026-06-30).

Highest expected annual loss (FEMA National Risk Index, modeled total; see B1-a): Inland Flooding ($5,444,993 a year), Cold Wave ($3,198,171) and Avalanche ($456,667).

Repetitive-loss flood properties now: FMA RL 0, SRL 0 (44 CFR 77.2); any definition: 0.

The tables that follow are organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B (B1-a to B2-c); each heading says which item its tables support.

Terms used

EAL:: expected annual loss: FEMA's modeled average yearly loss from a hazard.
NRI:: FEMA's National Risk Index (version 1.20, December 2025).
NFIP:: National Flood Insurance Program.
RL, SRL:: repetitive loss and severe repetitive loss: flood-insured properties with repeated claims (definitions in B2-c).
FMA, HMGP:: Flood Mitigation Assistance and Hazard Mitigation Grant Program, FEMA mitigation grants.
PA:: FEMA Public Assistance: disaster aid to governments and some nonprofits.
Zone-level:: NOAA logged the event for a National Weather Service forecast zone, which may include parts of neighboring counties.
County-coded:: NOAA logged the event to this county.
FIPS:: the federal code for a place; 30015 is this area.
D0 to D4:: U.S. Drought Monitor categories, from abnormally dry (D0) to exceptional drought (D4).
F/EF, EFU:: Fujita and Enhanced Fujita tornado ratings; EFU is an unrated tornado.
kt, CONUS:: knots (1 kt is about 1.15 mph); the contiguous United States.
CFR:: Code of Federal Regulations.
A4-a, E1-a:: other items of FEMA's Local Mitigation Plan Review Tool (sources, and changes since the last plan).
Dollars:: nominal (as reported, labeled with the year), not adjusted for inflation.

Plan clock

Status:: Approved, expires 2029-10-11
Plan:: Central Montana Regional Hazard Mitigation Plan 2024 (FEMA plan 109563)
Approved:: 2024-10-12
Days to expiry:: 1,107

What changed since your last plan (approved 2024-10-12)

New federal declarations:: none
Storm Events records since approval:: 82 records (data through 2026-06-30)
Repetitive loss now:: FMA RL 0, SRL 0 (44 CFR 77.2); any definition: 0
Repeat-flood change:: this release sets the baseline count.

Sources: 1, 2, 4, 6 (numbered list at the end)

Plan status for every jurisdiction listed in this county

Source: 1

Jurisdiction	Type	Status	Plan	Approved	Expires	Days to expirynegative = days since expiry	Notes
Chouteau County	County	Approved, expires 2029-10-11	Central Montana Regional Hazard Mitigation Plan 2024 (FEMA plan 109563)	2024-10-12	2029-10-11	1,107	this jurisdiction approved 2024-11-22
Big Sandy town	Town	Approved, expires 2029-10-11	Central Montana Regional Hazard Mitigation Plan 2024 (FEMA plan 109563)	2024-10-12	2029-10-11	1,107	this jurisdiction approved 2025-02-21
Fort Benton city	City	Approved, expires 2029-10-11	Central Montana Regional Hazard Mitigation Plan 2024 (FEMA plan 109563)	2024-10-12	2029-10-11	1,107	this jurisdiction approved 2024-11-22

Plan 109563 covers 40 other participants, named in the Excel file.

State plan status and tribal plans in this state: see the state page.

Supports FEMA checklist item B1-a: hazard identification

Hazards NRI does not cover (local data needed)

dam failure (incl. upstream dams)
levee failure
flash flood as its own subtype
ice jams
debris flows
erosion (riverine and coastal)
land subsidence and sinkholes
expansive soils

The 18 National Risk Index hazards, ranked by expected annual loss (EAL)

Sources: 5, 6

Rank by EAL	Hazard	NRI risk rating	EAL rating	EAL buildingsmodeled dollars per year	EAL agriculturemodeled dollars per year	Cost of expected deaths and injuriesFEMA's dollar value per year, not property damage	EAL total (see note)modeled dollars per year	Storm Events records, 1996 to 2026-06-30count	Why this hazard can be left outNRI Not Applicable, no declaration and no Storm Events record since 1996	Storm Events coverage note
1	Inland Flooding	Relatively Low	Relatively Low	$5,444,993	$0	$0	$5,444,993	10
2	Cold Wave	Relatively Moderate	Relatively Moderate	$17,197	$1,198,728	$1,982,246	$3,198,171	16
3	Avalanche	Relatively Moderate	Relatively Low	under $1	n/a	$456,667	$456,667	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
4	Wildfire	Relatively Low	Relatively Low	$166,928	$95	$5,467	$172,490	4
5	Lightning	Relatively Low	Relatively Low	$3,420	n/a	$147,518	$150,939	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
6	Drought	Relatively Low	Relatively Low	n/a	$112,913	n/a	$112,913	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
7	Winter Weather	Relatively Moderate	Relatively Moderate	$9,314	$395	$96,339	$106,047	145
8	Tornado	Very Low	Very Low	$67,729	$857	$4,215	$72,801	4
9	Strong Wind	Very Low	Very Low	$14,356	$8,214	$35,289	$57,859	333		Includes 192 High Wind and 1 Strong Wind records (NOAA non-thunderstorm wind types, outside NRI's Strong Wind definition).
10	Earthquake	Very Low	Very Low	$40,028	n/a	$4,700	$44,728			Storm Events does not record earthquakes.
11	Heat Wave	Very Low	Very Low	$23	$8,647	$26,061	$34,730	0		No recorded events in Storm Events since 1996 (data through 2026-06-30).
12	Hail	Very Low	Very Low	$8,384	$11,532	$1,315	$21,231	124
13	Ice Storm	Very Low	Very Low	$3,924	n/a	$401	$4,325	2
14	Landslide	Very Low	Very Low	$703	n/a	$210	$913	0		Declared 1 time; no Storm Events record of this type.
	Hurricane	Not Applicable	Not Applicable					0	NRI rates hurricane Not Applicable for this county, and no counted federal declaration for this county names it (EM-3253-MT names it but is not counted as a local occurrence; see B1-d).	No recorded events in Storm Events since 1996 (data through 2026-06-30).

Total = buildings + agriculture + population equivalence; FEMA values each expected death (or 10 injuries) at $13.7 million (2024 dollars).

NRI risk rating combines expected annual loss with social vulnerability and community resilience; EAL rating rates expected annual loss alone. Both compare this county with all U.S. counties.

Local data needed: state and local lightning and landslide records (Storm Events records these hazards only in part).

Not applicable to this county per NRI, with no federal declaration and no Storm Events record since 1996: coastal flooding, tsunami and volcanic activity. That is the evidence for leaving them out of the plan.

The state hazard mitigation plan also lists hazards for this county; FEMA asks the plan to explain any hazard it leaves out.

Supports FEMA checklist item B1-b: hazard location

Affects the whole county (national data give no location within it): Cold Wave, Drought, Hail, Heat Wave, Ice Storm, Lightning, Strong Wind and Winter Weather.

Inland Flooding: The FEMA Flood Insurance Rate Map (FIRM) is the required location source for flooding. See the FEMA Flood Map Service Center (https://msc.fema.gov) for this county.

Hazards that vary within the county: highest-rated census tracts

Source: 5

Hazard	Highest-rated census tractsNRI risk rating, score 0 to 100
Avalanche	tract 103 (Relatively Low, 77.8); tract 102 (Relatively Low, 75.0)
Earthquake	tract 103 (Relatively Low, 47.3); tract 102 (Relatively Low, 46.4)
Hurricane	no tract has a National Risk Index rating for this hazard
Landslide	tract 103 (Relatively Low, 93.1); tract 102 (Very Low, 72.8)
Tornado	tract 103 (Relatively Moderate, 54.0); tract 102 (Relatively Low, 30.1)
Wildfire	tract 103 (Relatively High, 96.5); tract 102 (Relatively Moderate, 90.0)

Up to 3 census tracts per hazard, highest National Risk Index rating first, then highest score; a tract number is the Census tract number (for example 103 is Census Tract 103). FEMA's Resilience Analysis and Planning Tool maps the National Risk Index for every tract: https://www.fema.gov/emergency-managers/practitioners/resilience-analysis-and-planning-tool

Supports FEMA checklist item B1-c: hazard extent

Extent: scale, observed range and worst recorded event per hazard

Sources: 6, 7

Hazard	Scale	Recordscount and years	Observed range	Worst recorded event	Most damaging (when different)	How it applies to jurisdictions	Note
Avalanche	none (count and damage only)	0					Physical measure: in event narratives only (local data needed).
Cold/Wind Chill, Extreme Cold/Wind Chill	wind chill	16 records, 2014 to 2025 (16 zone-level)	1 day to 5 days (median 1 day); 12 with a recorded value	5 consecutive days, 2022-12-19 to 2022-12-23, zone-level		Countywide (zone-level records).	Wind chill: in event narratives only (local data needed).
Frost/Freeze (outside NRI's Cold Wave definition)	crop damage	0					Temperature: in event narratives only (local data needed).
Drought	U.S. Drought Monitor scale (D0 to D4)	0					Storm Events enters a drought at D2 or worse east of the Rockies and D3 or worse from the Rockies west (NWS Instruction 10-1605); NRI drought counts D3 and D4 only.
Earthquake	Modified Mercalli (local data)	0					Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail	hail size (inches)	152 records, 1958 to 2025	0.75 in to 2.75 in (median 1 in); 152 with a recorded value	2.75 in hail, 2012-06-04; same size also recorded on 1988-07-05, 1992-07-23, 1997-06-06, 2000-07-05		Event records naming jurisdictions in the plan: Big Sandy town (18 records), Fort Benton city (16 records).
Excessive Heat, Heat	heat index (in event narratives)	0					Heat index: in event narratives only (local data needed).
Hurricane, Tropical Storm, Tropical Depression	Saffir-Simpson	0					Storm Events files every zone of a storm's episode under the storm's type; flooding from the storm is filed as Flood or Flash Flood records.
Ice Storm	Sperry-Piltz ice scale (local data)	2 records, 2009 to 2023 (2 zone-level)		No damage reported in 2 records.		Countywide (zone-level records).	Ice thickness: in event narratives only (local data needed).
Flash Flood, Flood, Lakeshore Flood	damage and flood days (flood depth: FIRM)	10 records, 2002 to 2024 (1 zone-level)		Flood, 2024-05-07, $194,000 property; $0 crops (2024 dollars)		Event records naming jurisdictions in the plan: Big Sandy town (1 record). Zone-level records (1) apply countywide.	Flood depth: see the FEMA Flood Insurance Rate Map. Storm Events damage is often $0 or blank for floods, major ones included; FEMA Public Assistance by declaration (B1-d) shows which floods cost the most.
Debris Flow	none (count and damage only)	0					Physical measure: in event narratives only (local data needed).
Lightning	annualized frequency (the measure FEMA's Local Mitigation Planning Handbook names)	0					Storm Events lists lightning with damage or casualties; physical measure in event narratives only (local data needed).
High Wind and Strong Wind (outside NRI's Strong Wind definition)	wind speed (kt and mph)	193 records, 1996 to 2026 (193 zone-level)	35 kt (40 mph) to 100 kt (115 mph) (median 54 kt (62 mph)); 193 with a recorded value	100 kt (115 mph) measured, High Wind, 2002-02-21; NWS zone MTZ013	High Wind, 1999-10-31, $300,000 property; crops not reported, reported for the zone (1999 dollars)	Countywide (zone-level records).
Thunderstorm Wind	wind speed (kt and mph)	155 records, 1957 to 2026	50 kt (58 mph) to 87 kt (100 mph) (median 52 kt (60 mph)); 144 with a recorded value	87 kt (100 mph) estimated, Thunderstorm Wind, 2002-07-14	Thunderstorm Wind, 1993-05-16, $50,000 property; crops not recorded (1993 dollars)	Event records naming jurisdictions in the plan: Big Sandy town (31 records), Fort Benton city (24 records).
Tornado	Enhanced Fujita (Fujita before Feb 2007)	15 records, 1960 to 2018	F/EF0 to F/EF3 (median F/EF0); 12 with a recorded value	F3 tornado, 1988-07-05, 3 mi path length (whole path, pre-1996), 200 yd wide, $250,000 property; crops not recorded (1988 dollars), 2 direct injuries	Tornado, 1965-07-10, $2,500,000 property; crops not recorded (1965 dollars)	No event record names a jurisdiction in the plan.	Before 1996 a tornado is listed once, under the county where it began, with its whole path's rating and length; from 1996 on, each county lists its own segment. Length is not used to rank tornadoes (see Methods).
Wildfire	acres burned (local data)	4 records, 2004 to 2026 (4 zone-level)		No damage reported in 4 records.		Countywide (zone-level records).	Acres burned: in event narratives only (local data needed).
Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet	none in data (snowfall: local data)	145 records, 1996 to 2026 (145 zone-level)		Blizzard, 2024-05-07, $114,000 property; $0 crops (2024 dollars); NWS zone MTZ317		Countywide (zone-level records).	Snow depth: in event narratives only (local data needed).

Storm Events records are more complete after 1996; before 1996 only Tornado (from 1950), Hail and Thunderstorm Wind (from 1955) exist. Zone-level records whose zone no NWS zone-county file places in this county (mostly before 2020) are not counted here (the Methods page explains the zone matching).

Dollars are nominal (as reported), labeled with the year; not adjusted for inflation.

Supports FEMA checklist item B1-d: previous occurrences

Federal declarations for this county: 10 declarations covering 7 separate hazard incidents counted in this packet (declarations for the same incident count once; non-natural and evacuation-only declarations are not counted).

Federal disaster declarations for this county

Sources: 1, 2, 3

Declared	Incident began	FEMA number	Type	Title	Mapped hazard	County Public Assistancefederal share obligated, nominal dollars	Flags	Notes
2024-07-18	2024-05-06	DR-4801-MT	Major disaster	Severe Winter Storm and Flooding	Inland Flooding; Winter Weather	$262,293.20	in the 12 months before plan approval; within last 5 years
2020-03-31	2020-01-20	DR-4508-MT	Major disaster	COVID-19 Pandemic	Non-natural, not counted	no Public Assistance recorded
2020-03-13	2020-01-20	EM-3476-MT	Emergency	COVID-19	Non-natural, not counted	no Public Assistance recorded		same incident as DR-4508
2013-07-10	2013-05-19	DR-4127-MT	Major disaster	Flooding	Inland Flooding	no Public Assistance recorded
2011-06-17	2011-04-04	DR-1996-MT	Major disaster	Severe Storms and Flooding	Inland Flooding	$229,150.51
2010-07-10	2010-06-15	DR-1922-MT	Major disaster	Severe Storms and Flooding	Inland Flooding	$81,649.48
2005-09-13	2005-08-29	EM-3253-MT	Emergency	Hurricane Katrina Evacuation	Hurricane: evacuation support, not a local hazard event; not counted	no Public Assistance recorded
2000-08-30	2000-07-13	DR-1340-MT	Major disaster	Wildfires	Wildfire	PA not declared for this county
1996-02-23	1996-02-04	DR-1105-MT	Major disaster	Severe Storms, Flooding, and Ice Jams	Inland Flooding	no Public Assistance recorded
1986-03-15	1986-02-24	DR-761-MT	Major disaster	Heavy Rains, Landslides & Flooding	Inland Flooding (primary); also designated: Landslide	no Public Assistance recorded

County Public Assistance: applicants the FEMA record places in this county, including any state agencies FEMA files there; statewide rows are listed on the state page; federal share obligated, nominal dollars.

Statewide declarations

Source: 2

Declared	Incident began	FEMA number	Type	Title	Mapped hazard
1964-12-18	1964-12-18	DR-182-MT	Major disaster	Severe Winter Storm	Winter Weather
1964-06-09	1964-06-09	DR-172-MT	Major disaster	Heavy Rains & Flooding	Inland Flooding
1953-06-06	1953-06-06	DR-5-MT	Major disaster	Floods	Inland Flooding

FEMA recorded these with designated area Statewide and no county, so they are listed on every county page in the state and not counted with county rows. Local data needed: whether each one affected this county.

11 Fire Management declarations (1973-08-16 to 1996-09-06) FEMA filed as Statewide with no county; each names one local fire. Listed on the state page.

Public Assistance not placed in any Montana county: 2 rows, $679,475.72; listed on the Montana state page.

Source: 3

Previous occurrences by hazard, with explicit no-event rows

Sources: 2, 6, 7

Hazard	Storm Events records, all years on file(years in the Period column)	Since plan approvalrecords	In the 12 months before plan approvalrecords	Last 5 yearsrecords	Declared incidents, all yearsseparate disasters	Period	Statement
Avalanche	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Cold Wave	16	5	3	13	0	1996 to 2026-06-30
Drought	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Earthquake	0	0	0	0	0		Storm Events does not record earthquakes; the USGS earthquake catalog is the source.
Hail	152	4	3	8	0	1955 to 2026-06-30
Heat Wave	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Hurricane	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Ice Storm	2	0	0	1	0	1996 to 2026-06-30
Inland Flooding	10	0	1	2	6	1996 to 2026-06-30
Landslide	0	0	0	0	1	1996 to 2026-06-30	No Storm Events records of this type; 1 federal declared incident (see declarations table)
Lightning	0	0	0	0	0	1996 to 2026-06-30	No recorded events, 1996 to 2026-06-30, NOAA NCEI Storm Events
Strong Wind	348	52	10	93	0	1955 to 2026-06-30	Includes 192 High Wind and 1 Strong Wind records.
Tornado	15	0	0	0	0	1950 to 2026-06-30
Wildfire	4	2	0	2	1	1996 to 2026-06-30
Winter Weather	145	19	12	44	1	1996 to 2026-06-30

Notable Storm Events records

Sources: 1, 6, 7

Date	Event type	Magnitude or extent	Damagenominal dollars	Deaths, injuriesdirect only	Location	Flags	Why listed
2024-05-07	Flood		$194,000 property; $0 crops (2024 dollars)	0, 0	BIG SANDY to BIG SANDY ARPT	in the 12 months before plan approval; within last 5 years	B1-c worst recorded: Flash Flood, Flood, Lakeshore Flood
2024-05-07	Blizzard		$114,000 property; $0 crops, reported for the zone (2024 dollars)	0, 0	NWS zone MTZ317 (LITTLE BELT AND HIGHWOOD MOUNTAINS), zone-level	in the 12 months before plan approval; within last 5 years	B1-c worst recorded: Winter Storm, Heavy Snow, Blizzard, Lake-Effect Snow, Winter Weather, Sleet
2022-12-19	Extreme Cold/Wind Chill		$0 property; $0 crops, reported for the zone (2022 dollars)	0, 0	NWS zone MTZ311 (BEARS PAW MOUNTAINS AND SOUTHERN BLAINE), zone-level	within last 5 years	B1-c worst recorded: Cold/Wind Chill, Extreme Cold/Wind Chill
2012-06-04	Hail	2.75 in	$0 property; $0 crops (2012 dollars)	0, 0	FLOWEREE		B1-c worst recorded: Hail
2002-07-14	Thunderstorm Wind	87 kt (100 mph) estimated	damage not reported	0, 0	FT BENTON		B1-c worst recorded: Thunderstorm Wind
2002-02-21	High Wind	100 kt (115 mph) measured	damage not reported	0, 0	NWS zone MTZ013 (CHOUTEAU), zone-level		B1-c worst recorded: High Wind and Strong Wind
1999-10-31	High Wind	76 kt (87 mph), measurement type not recorded	$300,000 property; crops not reported, reported for the zone (1999 dollars)	0, 0	Storm Events area BLAINE / CHOUTEAU / HILL (legacy zone code MTZ011), zone-level		B1-c most damaging: High Wind and Strong Wind
1998-06-19	Tornado	F1, 1 mi within this county, 20 yd wide	$50,000 property; crops not reported (1998 dollars)	0, 0	SHONKIN		large reported damage
1993-05-16	Thunderstorm Wind	speed not recorded	$50,000 property; crops not recorded (1993 dollars)	0, 0	Fort Benton		B1-c most damaging: Thunderstorm Wind
1988-07-05	Tornado	F3, 3 mi path length (whole path, pre-1996), 200 yd wide	$250,000 property; crops not recorded (1988 dollars)	0, 2	location not recorded		deaths or injuries recorded
1973-08-04	Tornado	F0, 0.1 mi path length (whole path, pre-1996), 10 yd wide	$25,000 property; crops not recorded (1973 dollars)	0, 0	location not recorded		large reported damage
1965-07-10	Tornado	no rating recorded, 0.2 mi path length (whole path, pre-1996), 33 yd wide	$2,500,000 property; crops not recorded (1965 dollars)	0, 5	location not recorded		deaths or injuries recorded

The full list is in the Excel file, sheet "B1-d Storm Events history" (692 rows).

Location is the place NOAA recorded, as written in its data; it need not be a jurisdiction in this plan.

Local data needed: state-declared emergencies, from your state emergency management agency (federal data do not include them).

Tribal and special-area declarations in this state are listed on the state page.

Supports FEMA checklist item B1-e: probability of future events

Probability: FEMA annualized frequency and descriptor per hazard

Sources: 5, 6

Hazard	FEMA annualized frequency (modeled)unit per row	Unit	In plain terms	Descriptor	Descriptor basis	NRI events or days in its record period (hail, wind and tornado are area-weighted, so can be fractional)	NRI period	Location	Note
Avalanche	0.0333	events per year	about 1 in 30 years	Possible	FEMA annualized frequency (modeled)	1	1994 to 2023 (30 years)	see B1-f
Cold Wave	9.12	event-days per year	about 9.12 days per year	Likely (from Storm Events: 7 of 30 years)	event-days in 7 of 30 years, 1996 to 2025 (23.3%)	173	2005-11-12 to 2024-11-12 (19 years)	countywide
Drought	65.4	event-days per year	about 65.4 days per year		event-days in 0 of 30 years, 1996 to 2025 (0%)	1,785	2000 to 2025 (25.25 years; D3 and D4 only)	countywide	No Storm Events drought record, 1996 to 2025
Earthquake	0.00109	annual probability at a location	chance a given location in the county has at least minor-damage shaking in a year: 0.109%			not shown	modeled	see B1-f	No descriptor (Storm Events does not record earthquakes).
Hail	0.984	events per year	about 0.98 per year	Likely	FEMA annualized frequency (modeled)	37.4 (modeled)	1986 to 2023 (38 years)	countywide
Heat Wave	1.37	event-days per year	about 1.37 days per year		event-days in 0 of 30 years, 1996 to 2025 (0%)	21.9	2005-11-12 to 2024-11-12 (19 years)	countywide	No Storm Events heat wave record, 1996 to 2025
Hurricane		events per year					1851 to 2024 (Atlantic)	see B1-f	Not Applicable in NRI for this county; no descriptor.
Ice Storm	0.0149	event-days per year	about 0.0149 days per year	Possible (from Storm Events: 2 of 30 years)	event-days in 2 of 30 years, 1996 to 2025 (6.67%)	0	1946-12-31 to 2014-02-12 (67 years)	countywide
Inland Flooding	0.286	event-days per year	about 0.286 days per year	Likely (from Storm Events: 7 of 30 years)	event-days in 7 of 30 years, 1996 to 2025 (23.3%)	8	1996 to 2023 (28 years)	see B1-f
Landslide	1.17	events per year (modeled)	about 1.17 per year	Highly likely	FEMA annualized frequency (modeled)	not shown	modeled	see B1-f
Lightning	24	days per year with a strike	about 24 days per year	Highly likely	FEMA annualized frequency (modeled)	not shown	1995 to 2023 (29 years; CONUS)	countywide
Strong Wind	0.803	events per year	about 0.8 per year	Likely	FEMA annualized frequency (modeled)	31	1986 to 2023 (38 years)	countywide
Tornado	0.251	events per year	about 1 in 4 years	Likely	FEMA annualized frequency (modeled)	not shown	1950 to 2023 (EF2+); 1986 to 2023 (EF0-1)	see B1-f
Wildfire	0.00057	annual probability at a location	chance a given location in the county burns in a year: 0.057%	Likely (from Storm Events: 3 of 30 years)	Storm Events records in 3 of 30 years, 1996 to 2025 (10%)	not shown	modeled	see B1-f	Descriptor from Storm Events, not NRI.
Winter Weather	28.7	event-days per year	about 28.7 days per year	Highly likely (from Storm Events: 30 of 30 years)	event-days in 30 of 30 years, 1996 to 2025 (100%)	546	2005-11-12 to 2024-11-12 (19 years)	countywide

FEMA annualized frequency (modeled) is the National Risk Index v1.20 (December 2025) estimate of how often a hazard affects this county in a year; it is not recorded events divided by years, and its unit differs by hazard (events, event-days, or days with a lightning strike per year). For earthquake, wildfire, coastal flooding and tsunami the value is the chance (or number of events) at a location in the county, not across the county, so no "1 in N years" is given and the descriptor comes from Storm Events where it has a record (none for earthquake). The Methods page gives each hazard's method, from FEMA's National Risk Index Technical Documentation v1.20.

Where NRI gives event-days, the descriptor comes from the share of years with a Storm Events record; NRI's source records more events, so the two differ.

Descriptor scale used in this packet (defined per unit)

Sources: 5, 6

Unit	Descriptor	Definition
events per year	Highly likely	1 or more per year
events per year	Likely	about once in 1 to 10 years
events per year	Possible	about once in 10 to 100 years
events per year	Unlikely	less than once in 100 years
annual probability	Likely	10% to under 100% chance in a given year
annual probability	Possible	1% to under 10% chance in a given year
annual probability	Unlikely	under 1% chance in a given year
event-days (share of years)	Highly likely	event-days recorded in 90% or more of years
event-days (share of years)	Likely	event-days recorded in 10% to under 90% of years
event-days (share of years)	Possible	event-days recorded in some years but under 10% of years
lightning strike-days	Highly likely	cloud-to-ground strikes on 1 or more days per year

Intensity bands: historical frequency (Storm Events)

Source: 6

Hazard	Band	Years	Eventscounty-coded records	Years in period	Events per yearevents / years
Hail	1.00-1.99 in	1996 to 2025	71	30	2.37
Hail	2.00 in+	1996 to 2025	13	30	0.433
Thunderstorm Wind (counted as NRI Strong Wind)	50-64 kt	1996 to 2025	116	30	3.87
Thunderstorm Wind (counted as NRI Strong Wind)	65 kt+	1996 to 2025	11	30	0.367
Thunderstorm Wind (counted as NRI Strong Wind)	unmeasured or below 50 kt	1996 to 2025	0	30	0
Tornado	EF0-1	1996 to 2025	4	30	0.133
Tornado	EF2-3	1996 to 2025	0	30	0
Tornado	EF4-5	1996 to 2025	0	30	0
Tornado	unrated (EFU)	1996 to 2025	0	30	0

The bands show how often events of each severity were recorded in this county, to profile how severe events have been (FEMA's probability item asks for the range of intensities).

Hail smaller than 1 inch is not counted: on 2010-01-05 the National Weather Service raised its severe-hail threshold from 3/4 inch to 1 inch, so smaller reports became less common after 2009 (NWS Service Change Notice 09-52). NRI hail frequency uses a 0.75 inch threshold.

Optional: future conditions. Not a required item in the 2025 FEMA Local Mitigation Planning Policy Guide; some states ask for it. The federal Climate Mapping for Resilience and Adaptation (CMRA) site gives county exposure to future climate conditions (https://resilience.climate.gov/).

Supports FEMA checklist item B1-f: hazards that vary across jurisdictions

Range of census tract risk within the county

Source: 5

Hazard	Tractsrated of all	NRI risk score, 0 to 100			Tracts by rating
Hazard	Tractsrated of all	Min	Median	Max	Tracts by rating
Avalanche	2 of 2	75.0	76.4	77.8	Relatively Low 2
Cold Wave	2 of 2	99.2	99.5	99.9	Very High 2
Drought	2 of 2	93.3	94.5	95.7	Relatively Moderate 2
Earthquake	2 of 2	46.4	46.8	47.3	Relatively Low 2
Hail	2 of 2	51.4	59.8	68.3	Relatively Low 2
Heat Wave	2 of 2	17.0	30.1	43.2	Relatively Low 2
Hurricane	0 of 2				Not Applicable 2
Ice Storm	2 of 2	20.0	32.6	45.1	Relatively Low 1, Very Low 1
Inland Flooding	2 of 2	98.3	98.4	98.5	Very High 2
Landslide	2 of 2	72.8	83.0	93.1	Relatively Low 1, Very Low 1
Lightning	2 of 2	92.5	95.8	99.2	Very High 1, Relatively High 1
Strong Wind	2 of 2	58.1	68.5	78.9	Relatively Moderate 2
Tornado	2 of 2	30.1	42.1	54.0	Relatively Moderate 1, Relatively Low 1
Wildfire	2 of 2	90.0	93.2	96.5	Relatively High 1, Relatively Moderate 1
Winter Weather	2 of 2	97.1	98.4	99.6	Very High 2

Drought: Agriculture is all of NRI's expected annual loss for this hazard in the county, so the tract range mostly reflects where crop and livestock value is.

Hail: Agriculture is 54% of NRI's expected annual loss for this hazard in the county, so the tract range mostly reflects where crop and livestock value is.

Rated tracts only: No Rating (score 0.0), Not Applicable and Insufficient Data tracts are counted but not used for the minimum, median and maximum.

The score ranks a tract against all U.S. tracts (100 = highest). The rating is FEMA's category for the tract's risk value, computed differently, so the two can disagree.

Frequency data for cold wave, drought, hail, heat wave, ice storm, lightning, strong wind and winter weather are county-wide or coarse (49 km grid or NWS zone), the same for every jurisdiction; the tract range mostly reflects where buildings and people are (crop and livestock value where a line above names agriculture).

This county has 2 census tracts; the minimum, median and maximum come from those 2.

Each jurisdiction (starting figures from federal data)

Sources: 1, 3, 4, 6

Jurisdiction	Type	Plan status	Repetitive lossFMA RL and SRL (44 CFR 77.2); repeat-flood, any definition	Public Assistance to this jurisdictionFEMA records matched by applicant name; federal share obligated, nominal dollars	Event records naming this placeall years; since its plan
Chouteau County	County	Approved, expires 2029-10-11	FMA RL 0, SRL 0; any 0	$537,288.06	0 total; 0 since its plan
Big Sandy town	Town	Approved, expires 2029-10-11	FMA RL 0, SRL 0; any 0	$35,805.13	50 total; 4 since its plan
Fort Benton city	City	Approved, expires 2029-10-11	FMA RL 0, SRL 0; any 0	no Public Assistance recorded	40 total; 0 since its plan

Repetitive-loss counts are for whole NFIP communities, which can extend beyond this county (see the note in B2-c).

Supports FEMA checklist items B2-a and B2-b: vulnerability and potential impacts

Local data needed

The table below gives county-level starting figures; the plan describes impacts for each jurisdiction and its own assets.

Critical facilities and lifelines per hazard
A problem statement per jurisdiction per hazard
Changes in development in hazard-prone areas since the last approval, or a statement of none (E1-a)
Future assets

County-level starter: exposure, expected annual loss and damage since the plan

Sources: 1, 2, 3, 5, 6, 7

Hazard	Building exposuremodeled dollars	Agriculture exposuremodeled dollars	Population exposedpeople	EAL buildingsmodeled dollars per year	EAL agriculturemodeled dollars per year	Cost of expected deaths and injuriesFEMA's dollar value per year, not property damage	EAL as % of exposurebuildings; agriculture where noted	Storm Events damage since 2024-10-12county-coded records, property plus crops, nominal dollars	Zone-level damage since planproperty plus crops, reported for the zone	Note
Avalanche	$180,446	n/a	10	under $1	n/a	$456,667	0.0001%
Cold Wave	$4,354,259,460	$219,736,153	5,879	$17,197	$1,198,728	$1,982,246	0.000395%		$0
Drought	n/a	$112,885,050	n/a	n/a	$112,913	n/a	0.1% (agriculture)			NRI has no building exposure for this hazard; agriculture shown
Earthquake	$7,900,807,264	n/a	5,895	$40,028	n/a	$4,700	0.000507%
Hail	$4,354,259,460	$219,736,153	5,879	$8,384	$11,532	$1,315	0.000193%	$0
Heat Wave	$4,354,259,460	$219,736,153	5,879	$23	$8,647	$26,061	under 0.0001%
Hurricane										Not Applicable in NRI for this county
Ice Storm	$4,354,259,460	n/a	5,879	$3,924	n/a	$401	under 0.0001%
Inland Flooding	$4,349,284,107	$0	0	$5,444,993	$0	$0	n/a (see note)			NRI counts the full building value of any census block with some flood loss; this is not the value of buildings in the floodplain. Use local FIRM overlays for B2-a/B2-b.
Landslide	$63,312,034	n/a	61	$703	n/a	$210	0.00111%
Lightning	$4,354,259,460	n/a	5,879	$3,420	n/a	$147,518	under 0.0001%
Strong Wind	$4,354,259,460	$219,736,153	5,879	$14,356	$8,214	$35,289	0.00033%	$0	$0
Tornado	$4,354,259,460	$219,736,153	5,879	$67,729	$857	$4,215	0.00156%
Wildfire	$721,603,080	$59,932,911	2,112	$166,928	$95	$5,467	0.0231%		$0
Winter Weather	$4,354,259,460	$219,736,153	5,879	$9,314	$395	$96,339	0.000214%		$0

Totals since 2024-10-12 (Storm Events through 2026-06-30): 24 county-coded records, 24 with a damage value recorded (including $0), $0; 58 zone-level records, 58 with a damage value recorded (including $0), $0 reported for the zone; Public Assistance: no counted declaration since the plan.

FEMA does not split Public Assistance by hazard. A declaration mapped to several hazards is listed under each of them with its full amount, so the per-hazard column does not add up to the total; the unit total counts each declaration once.

NRI computes earthquake exposure on its own basis, so it exceeds the county building value in B2-a.

Supports FEMA checklist item B2-a: vulnerability (county context)

County context

Source: 5

Measure	Value
Population	5,879
Building value (total, not at risk)	$4,354,259,460
Agriculture value (total, not at risk)	$219,736,153
NRI risk rating (all hazards)	Very Low
Expected annual loss, buildings and agriculture, all hazards	$7,118,382
Expected annual loss, population equivalence, all hazards (NRI values each statistical life at $13.7M; a modeled value of expected deaths and injuries, not property damage)	$2,760,428
Social vulnerability rating	Relatively High
Community resilience rating	Relatively Low
NRI version	December 2025

FEMA's all-hazard expected annual loss adds buildings, agriculture and population equivalence; this table gives the property part and the population-equivalence part as separate rows.

Social vulnerability: higher means people are more likely to be harmed and slower to recover. Community resilience: lower means the community is less able to recover. High social vulnerability and low resilience both raise the NRI risk rating.

Supports FEMA checklist item B2-c: repetitive loss properties

Repetitive loss in this county, both definitions

Sources: 1, 4

Definition	Properties	Severe repetitive loss	Properties
Repetitive loss, FMA definition (44 CFR 77.2)	0	Severe repetitive loss, FMA definition (44 CFR 77.2)	0
Repetitive loss, NFIP insurance definition	0	Severe repetitive loss, NFIP insurance definition	0

The state NFIP coordinator's list, the source FEMA's Handbook names, often uses the NFIP insurance definition (second row).

Repeat-flood properties: county total and NFIP communities

Sources: 1, 4

Scope	RL, FMAproperties	SRL, FMAproperties	RL, NFIPproperties	SRL, NFIPproperties	Any categoryproperties	Mitigatedproperties	Currently insuredproperties
County total	0	0	0	0	0	0	0

Repeat-flood properties by jurisdiction in the plan (NFIP community)

Sources: 1, 4

Jurisdiction	NFIP community ID	RL, FMAproperties	SRL, FMAproperties	RL, NFIPproperties	SRL, NFIPproperties	Any categoryproperties	Mitigatedproperties	Currently insuredproperties
Chouteau County	300011	0	0	0	0	0	0	0
Big Sandy town	300012	0	0	0	0	0	0	0
Fort Benton city	300013	0	0	0	0	0	0	0

Counts by occupancy group for each jurisdiction are in the Excel file, sheet "B2-c Jurisdictions".

Jurisdiction rows are whole NFIP communities and need not add up to the county total: a community that extends into another county is counted in full on each jurisdiction row, while the county table counts only its part in this county.

County repeat-flood properties by occupancy group: 0 in every occupancy group.

Sources: 1, 4

FMA RL and FMA SRL are the Flood Mitigation Assistance definitions (44 CFR 77.2), the ones the FEMA Local Mitigation Planning Policy Guide cites. NFIP repetitive loss (the FEMA insurance definition) is 2 or more claims over $1,000 in 10 years, and a property can leave that group once it is mitigated. Also shown: NFIP severe repetitive loss, any category, mitigated and currently insured. The Methods page gives the OpenFEMA field details.

Counts are aggregates of FEMA's public NFIP Multiple Loss Properties file (FEMA's data date 2026-08-02; file version 2026-08-04). No property is identified. County assignment is FEMA's geocode.

In this county 0 properties are FMA repetitive loss but not NFIP repetitive loss, and 0 properties are NFIP repetitive loss but not FMA repetitive loss.

Exact counts; no count suppression.

Sources

Tables cite these sources by number. The full list, for the plan's bibliography (FEMA review item A4-a):

FEMA, OpenFEMA HazardMitigationPlanStatuses v1, version 2026-09-29T134039Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/HazardMitigationPlanStatuses (API)
FEMA, OpenFEMA DisasterDeclarationsSummaries v2, version 2026-09-29T162832Z, pulled 2026-09-30, https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries (API)
FEMA, OpenFEMA PublicAssistanceFundedProjectsSummaries v1, version 2026-09-29T150754Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/PublicAssistanceFundedProjectsSummaries (API)
FEMA, OpenFEMA NfipMultipleLossProperties v1, version 2026-08-04T164045Z, pulled 2026-09-30, https://www.fema.gov/api/open/v1/NfipMultipleLossProperties (API)
FEMA, FEMA National Risk Index 1.20.0 (December 2025), county and census tract tables, version 1.20.0, pulled 2026-09-30, https://www.fema.gov/about/reports-and-data/openfema/nri/v120/NRI_Table_Counties.zip (download, 25 MB), https://www.fema.gov/about/reports-and-data/openfema/nri/v120/NRI_Table_CensusTracts.zip (download, 635 MB)
NOAA NCEI, NOAA NCEI Storm Events Database, details files (csvfiles v1.0), version c20260918, pulled 2026-09-30, https://www.ncei.noaa.gov/pub/data/swdi/stormevents/csvfiles/
NOAA National Weather Service, NWS county-public forecast zones correlation file, version bp03mr20 to bp16ap26 (11 files; newest bp16ap26), pulled 2026-09-30, https://www.weather.gov/gis/ZoneCounty
U.S. Census Bureau, Census 2024 Gazetteer, 2020 place by county, CT county-to-cousub crosswalk, version 2024-gazetteer, pulled 2026-09-30, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_counties_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_cousubs_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_place_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_unsd_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_elsd_national.zip, https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2024_Gazetteer/2024_Gaz_scsd_national.zip, https://www2.census.gov/geo/docs/reference/codes2020/national_place_by_county2020.txt, https://www2.census.gov/geo/docs/reference/ct_change/ct_cou_to_cousub_crosswalk.xlsx (used to match place names and codes; no table prints its values)

What this packet is and what the plan adds

This packet is the federal data for the plan's risk assessment, organized by the items of FEMA's Local Mitigation Plan Review Tool, Element B. Each section heading names the item its tables support; the plan and FEMA's review decide whether the item is met.

The plan adds what only the community has: local data on assets, critical facilities, development and each jurisdiction's impacts; local hazard history, including state-declared emergencies; the mitigation strategy; and adoption.

How the federal data are built: National Risk Index values are FEMA's model, not counts of events. Storm Events is more complete from 1996; zone-level records are placed by forecast zone, not by location in the county. Public Assistance for a jurisdiction is matched by applicant name. The Methods page gives every rule and the known edge cases.

OpenFEMA disclaimer

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

Reuse, citation and corrections

Reuse and citation: Hazard Plain text and tables are licensed under Creative Commons Attribution 4.0 International (CC BY 4.0, https://creativecommons.org/licenses/by/4.0/); credit Hazard Plain and the release. The underlying federal data are public domain; OpenFEMA data are also subject to the OpenFEMA terms and conditions.

Cite this: Hazard Plain (2026). Chouteau County, MT: risk-assessment baseline packet, release 2026-10 (data as of 2026-09-30; County FIPS 30015). Automated baseline. https://hazardplain.org/mt/30015/ Built from FEMA OpenFEMA, the FEMA National Risk Index and NOAA NCEI Storm Events; source versions in the packet's Sources list.

Corrections: to report an error, name the packet, the table and what your records show. Contact: contact@hazardplain.org

Hazard Plain release 2026-10. As of 2026-09-30; Storm Events data through 2026-06-30. Automated baseline.