Enter any address in Custer County, Idaho to see its FEMA flood zone
Flash flooding from monsoonal moisture is the dominant flood character in Custer County. Over the last 30 years, the NOAA Storm Events Database recorded 10 flash flood events and 8 flood events. Recent examples include flooding in early August 2021, driven by monsoonal moisture, and a June 2023 event where rainfall combined with snowmelt washed away a Forest Service road in the Salmon Challis National Forest.
While most flood insurance claims in Custer County have been in Zone X, averaging a $1,902 payout with 0.0 ft water depth, these events highlight the potential for flooding. Homeowners, particularly those located near waterways or in areas prone to rapid runoff from rain and snowmelt, should pay close attention to flood risk.
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.
Custer County, Idaho has recorded 18 flood-related events since 1996 according to NOAA's Storm Events Database, including 10 flash floods and 8 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 (1983–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Flooding, Landslides, And Mudslides | Flood | May 6, 2017 |
| Hurricane Katrina | Hurricane | Aug 29, 2005 |
| Wildfires | Fire | Jul 27, 2000 |
| Severe Storms, Snowmelt, Land/mud Slides, Flooding | Severe Storm | Mar 14, 1997 |
| Earthquake | Earthquake | Oct 28, 1983 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Sep 9, 2025 | 0.00K |
| Flood | Jun 12, 2023 | 20.00K |
| Flash Flood | Aug 2, 2021 | 0.00K |
| Flash Flood | Aug 1, 2021 | 0.00K |
| Flood | Mar 13, 2018 | 65.00K |
| Flood | Jun 1, 2018 | 10.00K |
| Flood | Feb 5, 2017 | 195.00K |
| Flood | May 1, 2017 | 3.50M |
| Flood | Mar 1, 2017 | 90.00K |
| Flood | Jun 1, 2017 | 900.00K |
Flash Flood — Sep 9, 2025
A mudslide occurred in Custer County on Bayhorse Creek Rd about 1 mile from the Bayhorse town site.
Flood — Jun 12, 2023
Forest Service road 135 washed away near the intersection of Bear Creek and Antelope Pass Roads. Rainfall combined with snow melt continued to create flooding in the Salmon Challis National Forest.
Flash Flood — Aug 2, 2021
Continued push of monsoonal moisture into Idaho caused continued flooding into the first couple of days of August.
Flash Flood — Aug 1, 2021
Continued push of monsoonal moisture into Idaho caused continued flooding into the first couple of days of August.
Flood — Mar 13, 2018
A return to heavy mountain snows in late February and early March added significantly to the snow pack especially in the Upper Snake River Highlands and snow melt and heavy rains occurred sporadically from the middle of the month onward. The worst of the flooding occurred in Clark and Madison which were both declared state disaster areas by the end of the month. Low elevations in the centra...
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 Custer 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 Custer 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.