Enter any address in Hamilton County, Illinois to see its FEMA flood zone
Flash flooding from thunderstorms is the primary flood hazard in Hamilton County. Between 1996 and 2023, NOAA Storm Events data recorded 31 flash flood events and 16 flood events. For example, torrential rainfall from slow-moving storms caused flooding issues in Hamilton County on July 19, 2025, and again on August 4, 2025.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone A and Zone UNKNOWN have experienced flood damage. Claims in Zone A averaged $4,522 with 1.0 ft of water depth, while claims in Zone UNKNOWN averaged $3,010 with 3.0 ft of water depth. Homeowners in areas designated as Zone A, or those whose flood zone is not yet determined, should pay particular attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
24 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Hamilton County, Illinois has recorded 47 flood-related events since 1996 according to NOAA's Storm Events Database, including 31 flash floods and 16 river or area floods. The county has received 10 federal disaster declarations. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1989–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storms And Flooding | Severe Storm | Apr 19, 2011 |
| Severe Storms, Flooding, And Tornadoes | Severe Storm | May 8, 2009 |
| Hurricane Katrina Evacuation | Hurricane | Aug 29, 2005 |
| Record/near Record Snow | Snowstorm | Dec 21, 2004 |
| Severe Storms, Tornadoes And Flooding | Tornado | Apr 21, 2002 |
| Severe Storms And Flooding | Severe Storm | Apr 28, 1996 |
| Severe Storms, Tornadoes & Flooding | Severe Storm | May 15, 1990 |
| Severe Storms & Tornadoes | Tornado | Jan 7, 1989 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | Jul 19, 2025 | 10.00K |
| Flood | Jul 19, 2025 | 0.00K |
| Flash Flood | Jul 19, 2025 | 5.00K |
| Flood | Aug 4, 2025 | 0.00K |
| Flash Flood | Aug 4, 2025 | 5.00K |
| Flood | Dec 29, 2024 | 0.00K |
| Flash Flood | Mar 24, 2023 | 0.00K |
| Flood | Jan 18, 2023 | 0.00K |
| Flash Flood | Jul 14, 2023 | 50.00K |
| Flash Flood | Feb 8, 2023 | 8.00K |
Flood — Jul 19, 2025
As high pressure slowly crept northward towards the Quad State region, ridging remained over the middle Mississippi River Valley. A slow-moving MCS moved through the northeastern half of the Quad State midday to near sunset. CAPE rose to 1000-2000J/kg in northern portions of Southern Illinois with effective bulk shear around 30kts. Extremely high moisture content with precipitable water values ...
Flash Flood — Jul 19, 2025
As high pressure slowly crept northward towards the Quad State region, ridging remained over the middle Mississippi River Valley. A slow-moving MCS moved through the northeastern half of the Quad State midday to near sunset. CAPE rose to 1000-2000J/kg in northern portions of Southern Illinois with effective bulk shear around 30kts. Extremely high moisture content with precipitable water values ...
Flood — Aug 4, 2025
A shortwave trough and closed low reached the Quad State from the northwest during the morning of the 4th. The arrival of the shortwave preceded peak heating by several hours, limiting convective potential. Shear was very weak and instability limited. Slow-moving storms did produce torrential rainfall, with flooding issues reported in Hamilton County.
Flash Flood — Aug 4, 2025
A shortwave trough and closed low reached the Quad State from the northwest during the morning of the 4th. The arrival of the shortwave preceded peak heating by several hours, limiting convective potential. Shear was very weak and instability limited. Slow-moving storms did produce torrential rainfall, with flooding issues reported in Hamilton County.
Flood — Dec 29, 2024
A rapidly developing low pressure system moved northeastward through the Quad State region from the evening of the 28th through the morning of the 29th. Minor flooding was observed in Hamilton County as a result of rainfall around an inch and a half falling on fairly saturated soils.
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 Hamilton County, Illinois:
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 Hamilton County, Illinois 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.