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Flood in Petroleum County, Montana
24 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.
Petroleum County, Montana, has 24 flood events in the NCEI record since 1950, with at least one in 13 different years.
May is the busiest month, with 7 of the recorded events. The last 20 years account for 20 events against 4 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 2% of the 1,175 flood events recorded in Montana; its 1.4 per 100 square miles compares with 0.8 statewide.
Compared with Montana
| Measure | Petroleum County | Montana | US |
|---|---|---|---|
| Flood events since 1950 | 24 | 1,175 | 183,559 |
| Per 100 square miles | 1.4 | 0.8 | 5.2 |
| Per 10,000 residents | 462.4 | 10.6 | 5.5 |
| Deaths recorded | 0 | 9 | 2,961 |
| Busiest month | May | June | June |
By year
Seasonality
0Feb
2Mar
4Apr
0May
7Jun
7Jul
1Aug
2Sep
0Oct
1Nov
0Dec
0
Recorded events
All 24 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 |
|---|---|---|---|---|---|---|---|
| 23 Jun 2023 | Flash Flood | — | — | — | — | — | County |
| 4 Jul 2022 | Flood | — | — | — | — | — | County |
| 26 Aug 2021 | Flood | — | — | — | — | — | County |
| 27 May 2019 | Flood | — | — | — | — | — | County |
| 1 Jun 2018 | Flood | — | — | — | — | — | County |
| 12 Mar 2018 | Flood | — | — | — | — | — | County |
| 4 Oct 2016 | Flood | — | — | — | — | — | County |
| 23 Aug 2014 | Flood | — | $515K | — | — | — | County |
| 3 Jun 2013 | Flood | — | — | — | — | — | County |
| 1 Jun 2011 | Flood | — | — | — | — | — | County |
| 23 May 2011 | Flood | — | — | — | — | — | County |
| 20 May 2011 | Flood | — | — | — | — | — | County |
| 20 May 2011 | Flood | — | — | — | — | — | County |
| 11 May 2011 | Flood | — | — | — | — | — | County |
| 10 May 2011 | Flood | — | — | — | — | — | County |
| 15 Mar 2011 | Flash Flood | — | — | — | — | — | County |
| 12 Mar 2011 | Flood | — | — | — | — | — | County |
| 14 Feb 2011 | Flash Flood | — | — | — | — | — | County |
| 13 Feb 2011 | Flood | — | — | — | — | — | County |
| 25 May 2008 | Flood | — | — | — | — | — | County |
| 27 Jun 2005 | Flash Flood | — | — | — | — | — | County |
| 16 Jun 2005 | Flash Flood | — | — | — | — | — | County |
| 15 Mar 2003 | Flash Flood | — | — | — | — | — | County |
| 10 Jun 1997 | Flash Flood | — | — | — | — | — | County |
Questions and answers
How many flood events has Petroleum County had?
24 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 Petroleum County?
23 Jun 2023 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Petroleum County?
The flood of 23 Aug 2014, with property damage estimated by NCEI at $515K.
How does Petroleum County compare with Montana for flood?
1.4 events per 100 square miles against 0.8 statewide; the county holds 24 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.