Enter any address in Boise County, Idaho to see its FEMA flood zone
Flash flooding from intense thunderstorms dominates flood events in Boise County. Over the last 30 years, NOAA Storm Events data shows 20 flash flood events compared to 7 general flood events. For example, monsoonal moisture led to slow-moving, intense storms on August 26, 2025, with near-record precipitable water levels. Another event on June 11, 2025, saw heavy rain over burn scars due to high moisture content and a passing trough.
While most flood events are flash floods, localized flooding can also occur due to snowmelt. On April 27, 2023, increased snowmelt following an above-average winter led to high streamflows and localized flooding, particularly near Centerville along Grimes Creek.
Homeowners in areas prone to rapid runoff, especially those near creeks or in locations with historical burn scars, should pay close attention to flood risks. Additionally, while Zone X properties have seen fewer claims, one claim averaged over $35,000, indicating potential financial exposure even in lower-risk zones.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
3 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Boise County, Idaho has recorded 27 flood-related events since 1996 according to NOAA's Storm Events Database, including 20 flash floods and 7 river or area floods. The county has received 7 federal disaster declarations, 1 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1964–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Karney Fire | Fire | Sep 18, 2012 |
| Hurricane Katrina | Hurricane | Aug 29, 2005 |
| Wildfires | Fire | Jul 27, 2000 |
| Severe Storms, Flooding, Mud And Landslides | Severe Storm | Nov 16, 1996 |
| Heavy Rains & Flooding | Flood | Dec 31, 1964 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Aug 26, 2025 | 0.00K |
| Flash Flood | Jun 11, 2025 | 0.00K |
| Flood | Apr 27, 2023 | 0.00K |
| Flood | Jun 5, 2022 | 0.00K |
| Flood | May 7, 2017 | 100.00K |
| Flash Flood | May 23, 2015 | 0.00K |
| Flood | Aug 6, 2014 | 0.00K |
| Flash Flood | Sep 5, 2013 | 0.00K |
| Flood | Jun 4, 2010 | 0.00K |
| Flash Flood | Jul 22, 2008 | 100.00K |
Flash Flood — Aug 26, 2025
Monsoonal moisture surged into the region over a three day period, the most intense of which was the 26th. High atmospheric moisture content combined with weak flow in a monsoonal pattern to produce very moist storms moving very slowly. Additionally, as terrain served as the main trigger for convection, storms would train over the same spots for much longer than normal. Precipitable water was a...
Flash Flood — Jun 11, 2025
On June 11th, a shortwave trough crossed across southwest Idaho aiding in thunderstorm development. RAP Mesoscale Analysis showed precipitable water values between 0.8 - 1 inch, around the climatological 95th percentile. With this moisture, heavy rain over burn scars was a primary hazard with storms that developed.
Flood — Apr 27, 2023
Several areas in the region experienced high streamflows at the end of April. Above average snowfall this winter led to increased snowmelt and localized flooding, especially near Centerville, ID with Grimes Creek.
Flood — Jun 5, 2022
Moist and unstable southwest flow moved into the region early on Sunday, June 5th. Favorable upper level dynamics combined with sufficient daytime heating led to several rounds of long-lasting severe thunderstorms through the overnight hours.
Flood — May 7, 2017
Spring snow melt flooding occurred across much of Southwest Idaho as a result of an above normal snow pack for the winter of 2016 to 2017.
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in Boise County, Idaho:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in Boise County, Idaho that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.