50 flood insurance claims·$645,518 paid·5 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, South Dakota. 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 and general flooding from summer storms dominate the flood risk profile in Custer County, SD, which recorded 21 flash flood events and 20 flood events over the last 30 years.
Recent events illustrate this localized threat. On September 13, 2023, a nearly stationary thunderstorm west of Hermosa dropped 2 to 5 inches of rainfall in under two hours, causing runoff that inundated several roads with water and debris. Earlier, on June 25, 2020, a slow-moving severe thunderstorm in the Custer area produced heavy rain and hail that accumulated six inches deep, triggering flash flooding on the east side of Custer.
Property owners located within FEMA Zone A should pay the most attention to flood risk, as this zone accounts for the vast majority of historical National Flood Insurance Program claims in the county with 46 recorded claims, an average payout of $17,313, and an average recorded water depth of 13 inches. Claims in Zone X_SHADED, Zone X, and Zone X_UNSHADED are significantly fewer, totaling only four claims combined across those categories.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
6% of Custer County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
49 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 13 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 2007, with 24 claims and $529,552 paid, the year of Severe Storms, Tornadoes, and Flooding.
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.
12 NOAA storm reports from Custer County describe what happened, in the words of the forecasters who covered it. Read the South Dakota flood stories →
16 federal disaster declarations since 1972, 5 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Qury Fire | Mar 12, 2026 |
| Severe Storms And Flooding | May 21, 2019 |
| Legion Lake Fire | Dec 12, 2017 |
| Severe Winter Storm, Snowstorm, And Flooding | Oct 3, 2013 |
| Myrtle Fire | Jul 19, 2012 |
| Hurricane Katrina Evacuation | Sep 6, 2005 |
| Sd - Battle Creek Fire - 08/18/02 | Aug 16, 2002 |
| Sd - Elk Mountain Fire Complex - 08/01/01 | Jul 30, 2001 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
41 since 1996: 21 flash floods and 20 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | Sep 13, 2023 | — |
| Flash Flood | Sep 13, 2023 | — |
| Flash Flood | Aug 24, 2022 | $20,000 |
| Flash Flood | Jun 25, 2020 | — |
| Flood | May 28, 2019 | $100,000 |
| Flood | May 21, 2019 | $100,000 |
| Flood | Jul 3, 2019 | — |
| Flood | Aug 2, 2019 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · Sep 13, 2023. A slow-moving thunderstorm briefly became severe over central Pennington County into north central Custer County, producing hail up to golf ball size along with heavy rainfall. The storm became nearly stationary just west of Hermosa and produced 2 to 5 inches of rainfall in less than 2 hours. Runoff from the heavy rainfall caused several roads to be inundated with water and debris west of Hermosa.
Flash Flood · Sep 13, 2023. A slow-moving thunderstorm briefly became severe over central Pennington County into north central Custer County, producing hail up to golf ball size along with heavy rainfall. The storm became nearly stationary just west of Hermosa and produced 2 to 5 inches of rainfall in less than 2 hours. Runoff from the heavy rainfall caused several roads to be inundated with water and debris west of Hermosa.
Flash Flood · Aug 24, 2022. A supercell thunderstorm developed over the southern Black Hills and tracked southeast, weakening on the adjacent plains. The storm produced large hail and heavy rain over the area. Other strong thunderstorms produced heavy rain and localized flash flooding over far southwestern South Dakota. Rain amounts of three to four inches were estimated in some areas. In Oglala Lakota County, flash flooding quickly occurred…
Flash Flood · Jun 25, 2020. A severe thunderstorm developed in the Custer area and remained nearly stationary for close to an hour and a half. The storm produced a lot of hail around quarter size, which accumulated six inches deep in some areas. The large amounts of hail and heavy rain also caused flash flooding on the east side of Custer.
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.