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Flood in Ada County, Idaho
23 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 23 flood events in Ada County, Idaho, between 1950 and 2026, spread over 15 years.
June is the busiest month, with 5 of the recorded events. The last 20 years account for 15 events against 8 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 2.9% of the 790 flood events recorded in Idaho; its 2.2 per 100 square miles compares with 1.0 statewide.
Compared with Idaho
| Measure | Ada County | Idaho | US |
|---|---|---|---|
| Flood events since 1950 | 23 | 790 | 183,559 |
| Per 100 square miles | 2.2 | 1.0 | 5.2 |
| Per 10,000 residents | 0.4 | 4.2 | 5.5 |
| Deaths recorded | 0 | 3 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
0Feb
1Mar
2Apr
2May
3Jun
5Jul
2Aug
4Sep
4Oct
0Nov
0Dec
0
Recorded events
All 23 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 |
|---|---|---|---|---|---|---|---|
| 26 Aug 2025 | Flash Flood | — | — | — | — | — | County |
| 13 Jun 2023 | Flood | — | — | — | — | — | County |
| 6 Jun 2023 | Flash Flood | — | $1.0M | $1.0M | — | — | County |
| 10 Aug 2022 | Flood | — | — | — | — | — | County |
| 1 Aug 2021 | Flash Flood | — | — | — | — | — | County |
| 30 Apr 2020 | Flash Flood | — | — | — | — | — | County |
| 1 May 2017 | Flood | — | $2.0M | — | — | — | County |
| 1 Apr 2017 | Flood | — | $1.0M | — | — | — | County |
| 6 Mar 2017 | Flood | — | — | — | — | — | County |
| 6 Mar 2017 | Flood | — | $1.0M | — | — | — | County |
| 8 Feb 2017 | Flood | — | — | — | — | — | County |
| 8 Jul 2015 | Flash Flood | — | $10K | — | — | — | County |
| 5 Sep 2013 | Flash Flood | — | — | — | — | — | County |
| 1 May 2012 | Flood | — | — | — | — | — | County |
| 3 May 2011 | Flood | — | — | — | — | — | County |
| 29 Jun 2004 | Flash Flood | — | — | — | — | — | County |
| 22 Aug 2003 | Flash Flood | — | — | — | — | — | County |
| 22 Jul 2002 | Flash Flood | — | — | — | — | — | County |
| 7 Sep 1998 | Flood | — | — | — | — | — | County |
| 6 Sep 1998 | Flood | — | — | — | — | — | County |
| 25 Jun 1998 | Flood | — | — | — | — | — | County |
| 12 Jun 1998 | Flood | — | — | — | — | — | County |
| 11 Sep 1997 | Flash Flood | — | $60K | — | — | — | County |
Questions and answers
How many flood events has Ada County had?
23 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 Ada County?
26 Aug 2025 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Ada County?
The flood of 1 May 2017, with property damage estimated by NCEI at $2.0M.
How does Ada County compare with Idaho for flood?
2.2 events per 100 square miles against 1.0 statewide; the county holds 23 of the state's 790 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.