Custer County, Idaho

What hazards hit Custer County most?

The most frequent records are winter storm records: 398 since 1996. 46% of its winter storm records since 1996 fell in December and January. The rank column places the county among Idaho's counties by days with a record per 1,000 square miles of land over each hazard's complete period.

Source: NOAA NCEI Storm Events Database (county and forecast-zone records attributed to the county; a zone record shows its own totals on each county it covers). Days: dates with at least one record of the hazard in the county. Ranks: days with a record per 1,000 square miles of land (Census Bureau 2024 Gazetteer), since 1950 for tornadoes, 1955 for hail and thunderstorm wind, 1996 for the rest.

How many tornadoes has Custer County had?

NOAA records 2 tornadoes in Custer County from 2008 to 2014, the strongest rated EF0, with 0 deaths and 0 injuries recorded in the county. A tornado that crossed a county line is counted in each county it touched, with the length of its path inside the county.

Counted as whole tornadoes rather than county records, the Storm Prediction Center's database holds 2 tornadoes whose track touched Custer County since 1950 (NOAA's county records number 2, the same count); along their whole tracks they killed 0 people.

Map of the strongest tornado tracks in Idaho.

Source: NOAA NCEI Storm Events Database, tornado records by county (path length in the county, maximum width); ratings as published: F scale before February 1, 2007, EF scale after. Whole-track figures: NOAA Storm Prediction Center tornado database (1950-2025). SPC severe weather database.

When was the last damaging storm in Custer County?

The most recent record with damage, injuries or deaths is the February 9, 2026 winter weather (1 injury).

Icy conditions caused multiple traffic accidents involving state Highway 75 commuters Monday morning. The Blaine County Sheriff's Office reported Monday morning that there had been three accidents which occurred around the Big Wood River bridge near St. Luke's Wood River Medical Center due to weekend rainfall creating black ice. One individual was later transported to the hospital for possible injuries sustained during an accident, according to a Sheriff's Office spokesperson. None of the accidents resulted in fatalities.
National Weather Service event narrative, NOAA Storm Events Database (search the full record, event 1320939)

Source: NOAA NCEI Storm Events Database; every record of 2025-2026 is listed, earlier ones when they caused deaths, injuries or $250,000 of damage (2025 dollars), and every tornado.

The deadliest and costliest records

Source: NOAA NCEI Storm Events Database: deaths and injuries direct and indirect; damage is property plus crops as estimated by the National Weather Service, converted to 2025 dollars.

Is it getting more frequent?

Records per decade for Custer County's most frequent hazards. Counts rose everywhere after 1996, when NOAA began recording every event type, so compare decades within a hazard's complete period only (the shaded cells come before it).

Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).

What time of year?

46% of its winter storm records since 1996 fell in December and January. The two busiest months are in violet.

Source: NOAA NCEI Storm Events Database, records by the month they began.

Federal disaster declarations for Custer County

FEMA's register lists 7 declarations that include Custer County: 5 major disasters, 2 emergencies and 0 fire management assistance declarations. Most were for biological (2) and flood (1).

Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), declarations through October 2, 2026; one declaration is counted once however many areas it names. OpenFEMA dataset page.

How many floods has Custer County had?

NOAA's Storm Events Database holds 20 flood or flash flood records for Custer County from 1997 to 2025, on 19 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Custer County ranks 2830th of 2,942 U.S. counties.

The National Flood Insurance Program has paid $1,902 on 1 claim filed in Custer County; the most in one year was 1 in 1997. Claims count insured losses only: uninsured flood damage is not in this file.

Source: FEMA OpenFEMA NFIP Redacted Claims, as of September 8, 2026; claims by year of loss, payments in the dollars of the year paid. OpenFEMA dataset page.

FEMA's modeled risk for Custer County

FEMA's National Risk Index rates Custer County Relatively Low overall, with an expected annual loss of $10.6 million. These are FEMA's model estimates of future loss from 18 hazards, not a count of what happened; they can differ from the record above.

Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.

Counties that share a border with Custer County

1. Butte County 788
2. Blaine County 688
3. Custer County 625
4. Elmore County 427
5. Lemhi County 350
6. Boise County 254
7. Valley County 231

Source: U.S. Census Bureau county adjacency file; NOAA NCEI Storm Events Database, records since 1950. The Census Bureau's adjacency file.

Next

• Tornadoes in IdahoEvery Idaho tornado since 1950 and the counties with the most per square mile
• Winter storms in IdahoThe state's winter storm records, by county, year and month
• The Idaho recordEvery hazard in the state, its deadliest events and its federal declarations
• FEMA's risk rating for each hazard in Custer CountyThe hazard risk calculator: 18 hazards beside the county's record
• Download Custer County's FEMA declarations (CSV)7 rows: every declaration that named the county, for your own analysis