Enter any address in Union County, Iowa to see its FEMA flood zone
Flash flooding from thunderstorms is the dominant flood character in Union County, IA. Between 1993 and 2023, the NOAA Storm Events Database recorded 26 flash flood events and 13 flood events in the county. For example, localized flash flooding occurred on July 11, 2015, when a warm front brought storms and heavy rainfall, with totals around 5.5-5.75 inches reported near Lorimor, Rathbun, Derby, and Humeston. More recently, on June 25, 2019, storms initiated along a stationary boundary across southern Iowa, leading to flash flooding.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone X have experienced the most claims, with an average payout of $17,532 and an average water depth of 3.0 feet. However, a single claim in Zone A resulted in a significantly higher average water depth of 48.0 feet, though with a lower average payout of $7,357. Properties in Zone X_SHADED also saw claims with an average water depth of 24.0 feet. Homeowners in areas designated as Zone A, Zone X_SHADED, and Zone X should pay the most attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
34 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Union County, Iowa has recorded 39 flood-related events since 1996 according to NOAA's Storm Events Database, including 26 flash floods and 13 river or area floods. The county has received 21 federal disaster declarations, 6 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 And Tornadoes | Tornado | Apr 26, 2024 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storms And Flooding | Flood | Mar 12, 2019 |
| Severe Storms, Flooding, And Tornadoes | Severe Storm | Jun 1, 2010 |
| Severe Winter Storm | Severe Storm | Jan 19, 2010 |
| Severe Storms, Tornadoes, And Flooding | Severe Storm | May 25, 2008 |
| Severe Winter Storm | Severe Ice Storm | Dec 10, 2007 |
| Severe Storms And Flooding | Severe Storm | Aug 17, 2007 |
| Severe Storms, Flooding, And Tornadoes | Severe Storm | May 5, 2007 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Jun 25, 2019 | 10.00K |
| Flash Flood | Sep 5, 2018 | 10.00K |
| Flood | Jul 11, 2015 | 100.00K |
| Flash Flood | Jul 11, 2015 | 50.00K |
| Flood | Sep 10, 2014 | 200.00K |
| Flash Flood | Sep 9, 2014 | 200.00K |
| Flash Flood | May 16, 2013 | 10.00K |
| Flash Flood | Jun 26, 2011 | 10.00K |
| Flash Flood | Jun 25, 2011 | 10.00K |
| Flash Flood | Jun 25, 2011 | 25.00K |
Flash Flood — Jun 25, 2019
During the evening of the 25th, a number of storms were able to initiate along a relatively stationary boundary situated across southern Iowa. On the warm side of the boundary surface conditions were in the mid 80s for temperature and upper 60s to low 70s dewpoints. Additionally, the conditions yielded an environment with 2000-3000+ J/kg SB/MUCAPE, 30-40 kts of effective bulk shear, 500-700 J/...
Flash Flood — Sep 5, 2018
Wet conditions continued across the state with yet another round of moderate to heavy rainfall on top of already mostly saturated conditions. A shortwave moving through the upper level flow out of the southwest, a surface front situated to the west and northwest of the state, and strong 850 mb flow were the main contributors to showers and storms. ||Conditions were certainly conducive for hea...
Flood — Jul 11, 2015
A warm front pushed into southern Iowa from Missouri, bringing with it storms and heavy rainfall. The front progressed slowly, aiding in keeping the rain over the same areas for long periods of time. By the end of the day, a number of areas across the south reported 4+ inches of rain with the highest totals around 5.5-5.75 near Lorimor, Rathbun, Derby, and Humeston. Localized flash flooding ...
Flash Flood — Jul 11, 2015
A warm front pushed into southern Iowa from Missouri, bringing with it storms and heavy rainfall. The front progressed slowly, aiding in keeping the rain over the same areas for long periods of time. By the end of the day, a number of areas across the south reported 4+ inches of rain with the highest totals around 5.5-5.75 near Lorimor, Rathbun, Derby, and Humeston. Localized flash flooding ...
Flood — Sep 10, 2014
Deep moisture moved into Iowa as a strong shortwave moved into the central U.S. Moisture from former hurricane Norbert moved into the central U.S. as a low pressure system developed over Kansas. The low from Kansas moved northeast into Iowa during the night of the 9th and morning of the 10th. The low was over southwest Wisconsin on the morning of the 10th. The atmosphere was unstable with 1...
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, Iowa:
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, Iowa 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.