156 flood insurance claims·$400,061 paid·2 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 Custer County, Montana. 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 profile of Custer County, accounting for 20 events compared to 11 general flood events over the last 30 years. Severe weather has repeatedly impacted the area, including a June 2025 multi-day storm sequence that prompted a state emergency declaration for Montana. Heavy rainfall from thunderstorms also triggered flash flooding on July 5, 2019, dropping 1 to 6 inches of rain that covered roadways and flooded basements.
National Flood Insurance Program records show claims spanning multiple zones, led by 74 claims in Zone UNKNOWN with an average payout of $3,850 and an average recorded water depth of 2 inches. Zone A accounts for 53 claims with an average payout of $2,679 and an average water depth of 2 inches, while Zone X_SHADED recorded 24 claims averaging $3,891 with an average water depth of 1 inch. Zone X recorded 4 claims with an average payout of $11,415 and an average water depth of 2 inches, and Zone X_UNSHADED logged 1 claim with $0 paid and 0 inches of recorded water depth.
Property owners in unmapped or poorly defined areas, designated as Zone UNKNOWN, along with those in designated Zone A flood hazard areas, should pay the closest attention to these risks given their high concentration of historical insurance claims.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
32% of Custer County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
78 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 2 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 1979, with 65 claims and $230,232 paid.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
4 NOAA storm reports from Custer County describe what happened, in the words of the forecasters who covered it. Read the Montana flood stories →
9 federal disaster declarations since 2000, 2 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Snider/rice Fire Complex | Sep 3, 2020 |
| Flooding | May 1, 2018 |
| Flooding | May 19, 2013 |
| Severe Storms And Flooding | Apr 4, 2011 |
| Severe Winter Storm | May 1, 2008 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
| Wildfires | Jul 13, 2000 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
31 since 1996: 20 flash floods and 11 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | Jun 15, 2025 | — |
| Flash Flood | May 24, 2023 | — |
| Flood | Aug 22, 2023 | — |
| Flash Flood | Jul 5, 2019 | — |
| Flash Flood | Jun 28, 2018 | — |
| Flash Flood | Jun 7, 2018 | — |
| Flash Flood | Jun 26, 2014 | — |
| Flood | Mar 6, 2014 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
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, besides water over ro…
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 Custer 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.