Enter any address in Custer County, Montana to see its FEMA flood zone
Flash flooding from thunderstorms is the dominant flood character in Custer County. Between 2003 and 2023, NOAA Storm Events data recorded 20 flash flood events and 11 general flood events. For example, heavy thunderstorms caused flash flooding across parts of the county on July 5, 2019, with rainfall ranging from 1 to 6 inches, leading to flooded basements and water over roadways. More recently, on May 24, 2023, scattered thunderstorms produced very heavy rain, contributing to flood events.
Homeowners in areas designated as Zone A or Zone X_SHADED should pay particular attention to flood risk. While Zone X_SHADED properties have shown an average water depth of 0.2 feet in claims, Zone A properties have averaged -1.1 feet. Properties in Zone UNKNOWN also represent a significant portion of claims, with an average payout of $3,290 and an average water depth of -0.9 feet.
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.
Custer County, Montana has recorded 31 flood-related events since 1996 according to NOAA's Storm Events Database, including 20 flash floods and 11 river or area floods. The county has received 9 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 (2000–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Snider/rice Fire Complex | Fire | Sep 3, 2020 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Flooding | Flood | May 1, 2018 |
| Flooding | Flood | May 19, 2013 |
| Severe Storms And Flooding | Severe Storm | Apr 4, 2011 |
| Severe Winter Storm | Severe Storm | May 1, 2008 |
| Hurricane Katrina Evacuation | Hurricane | Aug 29, 2005 |
| Wildfires | Fire | Jul 13, 2000 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | Jun 15, 2025 | 0.00K |
| Flash Flood | May 24, 2023 | 0.00K |
| Flood | Aug 22, 2023 | 0.00K |
| Flash Flood | Jul 5, 2019 | 0.00K |
| Flash Flood | Jun 28, 2018 | 0.00K |
| Flash Flood | Jun 7, 2018 | 0.00K |
| Flash Flood | Jun 26, 2014 | 0.00K |
| Flood | Mar 6, 2014 | 0.00K |
| Flood | May 30, 2013 | 0.00K |
| Flash Flood | May 18, 2013 | 0.00K |
Flood — Jun 15, 2025
This was the third day in a stretch of 4 days straight of severe storms across central and eastern MT. These storms caused damages resulting in a declaration of emergency for the state of Montana.
Flash Flood — May 24, 2023
A moist easterly surface flow, combined with a disturbance aloft, resulted in scattered thunderstorms across the Billings Forecast Area. Some of these thunderstorms produced very heavy rain and large hail.
Flood — Aug 22, 2023
A heavy thunderstorm that occurred in Miles City produced some street flooding.
Flash Flood — Jul 5, 2019
Very heavy thunderstorms moved across portions of southeast Montana during the afternoon and early evening hours of the 5th. Rainfall anywhere from 1 to 6 inches was reported across this area. In addition, large hail also occurred with a few of these thunderstorms. The rain and hail combined resulted in flash flooding across some areas. One location had a few basements flooded, but otherwise, b...
Flash Flood — Jun 28, 2018
During the late afternoon and evening hours on June 28th, severe weather broke out across much of the Billings Forecast Area. The most severe weather occurred across southeast Montana, mainly Carter County where golf ball size and larger hail, straight line winds 70-80 mph and four tornadoes were reported. ||Around 7:17 PM, the first tornado was spotted crossing SR 323 in Carter County about 12...
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, Montana:
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, Montana 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.