Enter any address in Lyon County, Iowa to see its FEMA flood zone
Flooding from heavy rainfall events is the dominant flood character in Lyon County. Between 2004 and 2024, NOAA Storm Events data recorded 89 flood events and 12 flash flood events. Recent heavy rainfall in June 2024 resulted in widespread totals of 5 to 10 inches across the region, leading to major to record river flooding and extensive overland flooding. Another event in June 2024 saw thunderstorms produce rainfall rates of 2 to 4 inches per hour, with 24-hour totals reaching 6 to 12 inches in Lyon and northern Sioux counties.
National Flood Insurance Program (NFIP) claims data from Lyon County shows that properties in Zone A have experienced the highest number of claims, with an average payout of $24,221 and an average water depth of 17.9 feet. Properties in Zone X also have a history of claims, averaging $21,066 with an average water depth of 3.1 feet. Residents in Zone A, Zone X, and those near streams and rivers should pay the most attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
29 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Lyon County, Iowa has recorded 101 flood-related events since 1996 according to NOAA's Storm Events Database, including 12 flash floods and 89 river or area floods. The county has received 16 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 (1965–2024)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Severe Storms, Flooding, Straight-line Winds, And Tornadoes | Severe Storm | Jun 16, 2024 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storms And Flooding | Flood | Mar 12, 2019 |
| Severe Storms, Tornadoes, Straight-line Winds, And Flooding | Severe Storm | Jun 6, 2018 |
| Severe Storms, Tornadoes, Straight-line Winds, And Flooding | Flood | Jun 14, 2014 |
| Severe Storms, Tornadoes, And Flooding | Severe Storm | May 19, 2013 |
| Severe Winter Storm | Severe Storm | Apr 9, 2013 |
| Severe Storms, Flooding, And Tornadoes | Severe Storm | Jun 1, 2010 |
| Severe Storms, Tornadoes, And Flooding | Severe Storm | May 25, 2008 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | Jun 21, 2024 | 0.00K |
| Flash Flood | Jun 21, 2024 | 0.00K |
| Flash Flood | Jun 20, 2024 | 0.00K |
| Flood | Jun 20, 2024 | 13.20M |
| Flood | Jul 1, 2024 | 0.00K |
| Flood | Apr 11, 2023 | 0.00K |
| Flood | Apr 10, 2023 | 0.00K |
| Flood | Mar 29, 2020 | 0.00K |
| Flood | Mar 28, 2020 | 0.00K |
| Flood | Mar 8, 2020 | 0.00K |
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 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 also resulted in significant impacts a...
Flash Flood — Jun 21, 2024
Clusters of thunderstorms with very high rainfall rates from 2 to 4 inches per hour developed by midday on June 20, and despite being transient, continued to redevelop through the evening and into the overnight hours. The primary focus occurred between Iowa Highway 9 and U.S. Highway 18 as the effective cold pool boundary collapsed southward and locked in place through the night. The final 24 h...
Flash Flood — Jun 20, 2024
Clusters of thunderstorms with very high rainfall rates from 2 to 4 inches per hour developed by midday on June 20, and despite being transient, continued to redevelop through the evening and into the overnight hours. The primary focus occurred between Iowa Highway 9 and U.S. Highway 18 as the effective cold pool boundary collapsed southward and locked in place through the night. The final 24 h...
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 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 also resulted in significant impacts a...
Flood — Jul 1, 2024
River levels from the historic June flooding remained above flood stage for some locations into July, although continued a declining trend.
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 Lyon 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 Lyon 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.