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Flood in Custer County, Montana
31 floods and flash floods events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Flood, Flash Flood, Coastal Flood, Lakeshore Flood.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 31 flood events in Custer County, Montana, between 1950 and 2026, spread over 15 years.
June is the busiest month, with 12 of the recorded events. The last 20 years account for 19 events against 12 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 2.6% of the 1,175 flood events recorded in Montana; its 0.8 per 100 square miles compares with 0.8 statewide.
Compared with Montana
| Measure | Custer County | Montana | US |
|---|---|---|---|
| Flood events since 1950 | 31 | 1,175 | 183,559 |
| Per 100 square miles | 0.8 | 0.8 | 5.2 |
| Per 10,000 residents | 26.0 | 10.6 | 5.5 |
| Deaths recorded | 0 | 9 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
0Feb
0Mar
1Apr
0May
7Jun
12Jul
9Aug
2Sep
0Oct
0Nov
0Dec
0
Recorded events
All 31 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 15 Jun 2025 | Flood | — | — | — | — | — | County |
| 22 Aug 2023 | Flood | — | — | — | — | — | County |
| 24 May 2023 | Flash Flood | — | — | — | — | — | County |
| 5 Jul 2019 | Flash Flood | — | — | — | — | — | County |
| 28 Jun 2018 | Flash Flood | — | — | — | — | — | County |
| 7 Jun 2018 | Flash Flood | — | — | — | — | — | County |
| 26 Jun 2014 | Flash Flood | — | — | — | — | — | County |
| 6 Mar 2014 | Flood | — | — | — | — | — | County |
| 11 Jun 2013 | Flash Flood | — | — | — | — | — | County |
| 30 May 2013 | Flood | — | — | — | — | — | County |
| 18 May 2013 | Flash Flood | — | — | — | — | — | County |
| 11 Jun 2011 | Flood | — | — | — | — | — | County |
| 20 May 2011 | Flood | — | $1.1M | — | — | — | County |
| 10 May 2011 | Flood | — | — | — | — | — | County |
| 25 May 2010 | Flood | — | $130K | — | — | — | County |
| 7 Jun 2007 | Flood | — | — | — | — | — | County |
| 6 Jun 2007 | Flash Flood | — | — | — | — | — | County |
| 6 Jun 2007 | Flash Flood | — | — | — | — | — | County |
| 6 Jun 2007 | Flash Flood | — | — | — | — | — | County |
| 20 Jun 2005 | Flash Flood | — | — | — | — | — | County |
| 8 May 2005 | Flash Flood | — | — | — | — | — | County |
| 10 Jul 2004 | Flash Flood | — | — | — | — | — | County |
| 30 Jun 2004 | Flood | — | — | — | — | — | Forecast zone |
| 6 Jul 2002 | Flash Flood | — | — | — | — | — | County |
| 31 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 31 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 26 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 25 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 11 Aug 1999 | Flood | — | — | — | — | — | County |
| 4 Jul 1998 | Flash Flood | — | — | — | — | — | County |
| 4 Jul 1998 | Flash Flood | — | $1.0M | — | — | — | County |
Questions and answers
How many flood events has Custer County had?
31 events in the NCEI Storm Events record between 1950 and 2026. Reporting of floods and flash floods became far more complete after 1996, so early decades undercount.
When was the last recorded flood event in Custer County?
15 Jun 2025 (Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Custer County?
The flood of 20 May 2011, with property damage estimated by NCEI at $1.1M.
How does Custer County compare with Montana for flood?
0.8 events per 100 square miles against 0.8 statewide; the county holds 31 of the state's 1,175 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Flood hub and the county page.