Enter any address in Ada County, Idaho to see its FEMA flood zone
Flash flooding from slow-moving thunderstorms dominates flood events in Ada County. Over the last 30 years, NOAA Storm Events data shows 14 flood events and 10 flash flood events. Recent examples include flash flooding on August 26, 2025, caused by monsoonal moisture and slow-moving storms, and heavy rain leading to flooded streets and stranded vehicles in Boise on June 6, 2023.
FEMA data indicates that properties in Zone A and Zone X have experienced the most National Flood Insurance Program (NFIP) claims. While Zone A properties had a higher number of claims, Zone X properties, particularly Zone X_UNSHADED, saw significantly higher average payouts and water depths, suggesting a greater potential for substantial damage. Homeowners in these zones, as well as those in Zone X_SHADED, should pay close attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
4 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Ada County, Idaho has recorded 24 flood-related events since 1996 according to NOAA's Storm Events Database, including 10 flash floods and 14 river or area floods. The county has received 6 federal disaster declarations, 2 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 |
| Flooding | Flood | Mar 29, 2017 |
| Hurricane Katrina | Hurricane | Aug 29, 2005 |
| Wildfires | Fire | Jul 27, 2000 |
| 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 |
| Flood | Jun 13, 2023 | 0.00K |
| Flash Flood | Jun 6, 2023 | 1000.00K |
| Flood | Aug 10, 2022 | 0.00K |
| Flash Flood | Aug 1, 2021 | 0.00K |
| Flash Flood | Apr 30, 2020 | 0.00K |
| Flood | Feb 8, 2017 | 0.00K |
| Flood | Mar 6, 2017 | 0.00K |
| Flood | Mar 6, 2017 | 1.00M |
| Flood | May 1, 2017 | 2.00M |
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...
Flood — Jun 13, 2023
A nearly stationary upper level low over the Four Corners region brought periods of heavy rain and thunderstorms which caused localized urban flooding in south central Idaho. Rainfall totals were around 0.50 inches, but the previous days rainfall made areas more prone to localized flooding.
Flash Flood — Jun 6, 2023
Thunderstorms developed across southwest Idaho early Tuesday evening and produced |heavy rain and strong winds across portions of the Lower Treasure Valley, including the city of Boise. Social media, weather spotters, and emergency manager reports indicated flooding of many streets in downtown Boise and the North-End Boise area. Water overwhelmed storm water drainages and flowed onto sidewalks...
Flood — Aug 10, 2022
An upper level trough on the West Coast slowly edged in between a ridge of high pressure to the east of the region. This allowed for monsoon moisture to move into the region along with strong southwest flow. Several days of isolated supercells occurred, bringing heavy rain and large hail to the region.
Flash Flood — Aug 1, 2021
Monsoonal moisture associated with a low pressure system brought locally heavy rain and thunderstorms to southwestern Oregon and southeastern Idaho. Flash flood watches were issued to the area due to the extensive precipitation.
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 Ada 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 Ada 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.