Enter any address in Union County, South Dakota to see its FEMA flood zone
Flood events, including flash floods, are a recurring concern in Union County, South Dakota. Between 1993 and 2023, NOAA Storm Events data recorded 141 flood events and 19 flash flood events. Recent heavy rainfall events have caused significant impacts. For example, a multi-day rainfall event in June 2024 resulted in widespread totals of 5 to 10 inches, with some areas exceeding 15 inches, leading to major river flooding and extensive overland flooding. In July 2023, a cluster of thunderstorms produced 2 to 5 inches of rain in a short period, causing significant flash flooding in impacted neighborhoods.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone X have experienced the most claims, with an average payout of $12,550 and an average water depth of 2.3 feet. Properties in Zone A have seen fewer claims but with higher average payouts ($22,762) and deeper water (5.0 feet). Homeowners in areas designated as Zone A, as well as those located near rivers or in areas prone to overland flooding, should pay particular attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
45 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Union County, South Dakota has recorded 160 flood-related events since 1996 according to NOAA's Storm Events Database, including 19 flash floods and 141 river or area floods. The county has received 19 federal disaster declarations, 10 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1969–2024)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Severe Storms, Straight-line Winds, And Flooding | Flood | Jun 16, 2024 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storms, Tornadoes, And Flooding | Severe Storm | Sep 9, 2019 |
| Severe Storms And Flooding | Flood | May 21, 2019 |
| Severe Winter Storm, Snowstorm, And Flooding | Flood | Mar 13, 2019 |
| Severe Storms, Tornadoes, And Flooding | Flood | Jun 13, 2014 |
| Severe Storms, Tornado, And Flooding | Severe Storm | May 24, 2013 |
| Flooding | Flood | Mar 11, 2011 |
| Severe Storms And Flooding | Severe Storm | Sep 22, 2010 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Jul 24, 2025 | 0.00K |
| Flood | Jun 24, 2024 | 0.00K |
| Flood | Jun 23, 2024 | 0.00K |
| Flood | Jun 21, 2024 | 0.00K |
| Flood | Jun 21, 2024 | 54.52M |
| Flood | Jun 20, 2024 | 0.00K |
| Flood | Jul 1, 2024 | 0.00K |
| Flood | Mar 16, 2023 | 0.00K |
| Flood | Apr 12, 2023 | 0.00K |
| Flood | Apr 10, 2023 | 0.00K |
Flash Flood — Jul 24, 2025
A cluster of thunderstorms erupted within a very moist and unstable airmass ahead of a slow moving frontal boundary during the evening of July 23. These thunderstorms bisected the city of Sioux Falls from southwest to northeast with neighborhoods southeast of I-229 reporting 2 to 5 inches of rain in a matter of 1-2 hours. This resulted in significant flash flooding across impacted portions of t...
Flood — Jun 24, 2024
A multi-day significant heavy rainfall event from June 20-22 resulted in widespread rain totals between 5 and 10 inches with pockets in excess of 15 inches across portions of southeast South Dakota, northwest Iowa, and southwest Minnesota. As rainfall reached area streams and rivers, major to record flooding was observed, devastating several towns and communities. Extensive overland flooding al...
Flood — Jun 23, 2024
A multi-day significant heavy rainfall event from June 20-22 resulted in widespread rain totals between 5 and 10 inches with pockets in excess of 15 inches across portions of southeast South Dakota, northwest Iowa, and southwest Minnesota. As rainfall reached area streams and rivers, major to record flooding was observed, devastating several towns and communities. Extensive overland flooding al...
Flood — Jun 21, 2024
A multi-day significant heavy rainfall event from June 20-22 resulted in widespread rain totals between 5 and 10 inches with pockets in excess of 15 inches across portions of southeast South Dakota, northwest Iowa, and southwest Minnesota. As rainfall reached area streams and rivers, major to record flooding was observed, devastating several towns and communities. Extensive overland flooding al...
Flood — Jun 20, 2024
A multi-day significant heavy rainfall event from June 20-22 resulted in widespread rain totals between 5 and 10 inches with pockets in excess of 15 inches across portions of southeast South Dakota, northwest Iowa, and southwest Minnesota. As rainfall reached area streams and rivers, major to record flooding was observed, devastating several towns and communities. Extensive overland flooding al...
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 Union County, South Dakota:
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 Union County, South Dakota 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.