1 flood insurance claims·$35,645 paid·1 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Boise County, Idaho. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flash flooding from summer thunderstorms dominates the flood risk in Boise County, ID, accounting for 20 of the 27 recorded flood events over the last 30 years, alongside 7 general flood events.
Recent events illustrate these primary hazards. On August 26, 2025, a monsoonal moisture surge with near-record precipitable water levels produced very moist, slow-moving storms that trained over the same terrain. Earlier that year on June 11, 2025, a shortwave trough brought heavy rain over burn scars in the region. Additionally, above-average winter snowfall led to increased snowmelt and localized flooding near Centerville along Grimes Creek on April 27, 2023. FEMA records show limited historical National Flood Insurance Program claims, with a single claim logged in Zone X resulting in an average payout of $35,645 and an average recorded water depth of 0 inches.
Homeowners and real estate agents with properties near burn scars, terrain-driven storm paths, and creeks such as Grimes Creek near Centerville should pay the most attention to this flood risk.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
3 NOAA storm reports from Boise County describe what happened, in the words of the forecasters who covered it. Read the Idaho flood stories →
7 federal disaster declarations since 1964, 1 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Karney Fire | Sep 18, 2012 |
| Hurricane Katrina | Aug 29, 2005 |
| Wildfires | Jul 27, 2000 |
| Severe Storms, Flooding, Mud And Landslides | Nov 16, 1996 |
| Heavy Rains & Flooding | Dec 31, 1964 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
27 since 1996: 20 flash floods and 7 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Aug 26, 2025 | — |
| Flash Flood | Jun 11, 2025 | — |
| Flood | Apr 27, 2023 | — |
| Flood | Jun 5, 2022 | — |
| Flood | May 7, 2017 | $100,000 |
| Flash Flood | May 23, 2015 | — |
| Flood | Aug 6, 2014 | — |
| Flash Flood | Sep 5, 2013 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
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 at near record levels…
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.
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Boise County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.