347 flood insurance claims·$4.4M paid·10 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 Hamlin 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.
River and general floods from summer thunderstorms dominate the flood character of Hamlin County, supported by 51 flood events, 18 flash floods, and 8 lakeshore flood events recorded over the last 30 years by the NOAA Storm Events Database. Recent historical impacts include heavy rainfall from persistent thunderstorms in July 2025 that followed severe storm activity, as well as intense heavy rainfall events on August 17 and August 22, 2025, which caused flooding after weeks of wet weather and saturated soils, with 3 inches of rain recorded in Lake Poinsett and 1.5 inches in Hayti.
National Flood Insurance Program records show claims across multiple zones, led by Zone X_UNSHADED with 160 claims averaging a $16,623 payout and an average recorded water depth of 4 inches, and Zone X with 130 claims averaging a $16,299 payout and an average recorded water depth of 2 inches. Zone A accounts for 39 claims averaging an $11,672 payout and an average recorded water depth of 5 inches, while Zone UNKNOWN has 17 claims averaging $6,201 with an average water depth of 1 inch, and Zone D records 1 claim averaging $15,000 with a 1-inch average depth. Homeowners and real estate agents with properties in unshaded and shaded Zone X, as well as Zone A, should pay the most attention to flood risk given the concentration of past claims and recorded water depths.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
80% of Hamlin County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
199 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 3 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 2011, with 107 claims and $1.8M paid, the year of 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.
26 NOAA storm reports from Hamlin County describe what happened, in the words of the forecasters who covered it. Read the South Dakota flood stories →
22 federal disaster declarations since 1969, 10 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Winter Storms And Snowstorm | Dec 12, 2022 |
| Severe Storm, Straight-line Winds, Tornadoes, And Flooding | May 12, 2022 |
| Severe Storms And Flooding | May 21, 2019 |
| Severe Winter Storm, Snowstorm, And Flooding | Mar 13, 2019 |
| Severe Winter Storm | Dec 24, 2016 |
| Severe Storms, Tornadoes, And Flooding | Jun 19, 2013 |
| Flooding | Mar 11, 2011 |
| Flooding | Mar 10, 2010 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
77 since 1996: 18 flash floods, 51 river or area floods and 8 coastal floods or surges.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Jun 28, 2025 | — |
| Flood | Jul 27, 2025 | — |
| Flood | Aug 22, 2025 | — |
| Flood | Aug 17, 2025 | — |
| Flood | Aug 6, 2025 | — |
| Flood | Aug 1, 2025 | — |
| Flood | May 23, 2024 | — |
| Flood | Jun 23, 2024 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · Jun 28, 2025. A volatile atmospheric setup on the afternoon and evening of June 28th led to the development of several powerful supercell thunderstorms across far eastern South Dakota. These storms produced multiple tornadoes, including two that caused significant damage in Deuel County. The strongest tornado was rated as a high-end EF3. Storms also produced large hail and instances of flash flooding from heavy rainfall.
Flood · Jul 27, 2025. An afternoon thunderstorm developed near the town of Henry and very quickly spun up a violent tornado. This tornado would cause significant damage to a farmstead before dissipating. The storm would go on to produce large hail, up to the size of baseballs near Lake Kampeska, with numerous additional reports of golf-ball sized hail, in and around the city of Watertown. The Watertown Automated Surface Observing Syste…
Flood · Aug 22, 2025. Storms moved over portions of northeast South Dakota that had really no extra room for moisture from the preceding months of nearly constant rainfall. Thus, this moisture went straight into the Big Sioux and tributaries from the Watertown area down south to Castlewood. The COOP observer in Rauville would record 1.51 inches of rainfall pushing their monthly total up to 5.73 and a 3 month total of 23.32. The Waterto…
Flood · Aug 17, 2025. Brief but intense heavy rainfall from thunderstorms, on top of weeks of wet weather, resulted in additional flooding across Marshall, Hamlin, Codington, and Deuel counties starting on the 17th and persisting well into the 18th. An estimated 3 inches of rain fell in Lake Poinsett, while 1.63 inches was recorded by the COOP sensor 20 miles north northeast of Aberdeen, 1.62 inches was submitted by the CoCoRaHS volun…
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 Hamlin 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.