This interactive map shows FEMA flood zones across Illinois, drawn directly from the National Flood Hazard Layer (NFHL). Illinois is an inland state, so its flood risk is dominated by riverine flooding – rivers, creeks, and heavy-rainfall events overwhelming local drainage rather than coastal storm surge. Use the map to see Special Flood Hazard Areas, coastal V and VE zones (where applicable), the 500-year (Zone X) floodplain, and regulatory floodways – the data is identical to what underwrites the National Flood Insurance Program.

Flood risk overview for Illinois

• Inland (riverine) flood risk: FEMA rates Illinois as Relatively High, with an expected annual loss of $2.92 billion/year from rivers, creeks, and rainfall flooding.
• Combined flood expected annual loss across Illinois: $2.92 billion per year, based on FEMA’s December 2025 National Risk Index.
• Population in mapped flood-exposed areas: roughly 231,136 Illinois residents live in mapped riverine flood zones.
• Recorded historical flood events: 1,477 inland flood events in the NRI source record.

FEMA’s National Risk Index ratings range from Very Low through Very High. Ratings reflect the state’s expected annual economic loss from each hazard, normalised against the rest of the country.

Interactive map of Illinois flood zones

The map below opens centred on Illinois. FEMA flood zone polygons load at zoom level 11 and above – this is a hard limit set by the source dataset, which contains over 51 GB of polygon geometry. Use the +/- controls or scroll to zoom in until polygons appear, then pan to any address in the state. Click a polygon for the full zone designation, SFHA status, and base flood elevation where available.

Illinois counties with the highest flood risk

FEMA’s National Risk Index aggregates flood loss expectations to the county level. The Illinois counties below carry the largest combined inland + coastal expected annual loss from flooding:

Recent flood-related federal disaster declarations in Illinois

Federal disaster declarations covering flood, severe storm, hurricane, and coastal storm events affecting Illinois in the last decade. Each declaration unlocks federal Public Assistance, Individual Assistance, and Hazard Mitigation funding for the designated counties.

• DR-4819 (Sep 2024): Severe Storms, Tornadoes, Straight-Line Winds, And Floodng – 7 designated counties/areas
• DR-4749 (Nov 2023): Severe Storms And Flooding
• DR-4728 (Aug 2023): Severe Storms And Flooding – 22 designated counties/areas
• DR-4676 (Oct 2022): Severe Storm And Flooding
• DR-4461 (Sep 2019): Severe Storms And Flooding – 28 designated counties/areas

Source: OpenFEMA Disaster Declarations Summaries.

How to look up the FEMA flood zone for a Illinois address

The map on this page is for general orientation. For an authoritative flood zone determination on any specific Illinois property – which is what mortgage lenders, insurance underwriters, and permitting offices use – go to the FEMA Map Service Center, search by address, and download the effective Flood Insurance Rate Map (FIRM) or generate a FIRMette for that location. This is the only legally recognised flood zone determination in Illinois.

Flood zone categories on the Illinois map

• Floodway – the channel of a river plus floodplain that must remain clear to carry the base flood. Construction in floodways is severely restricted across Illinois.
• Zone AE – the most common Special Flood Hazard Area in Illinois. Has a published Base Flood Elevation. Mandatory flood insurance for federally backed mortgages.
• Zone A – SFHA without a published base flood elevation; common in less-studied parts of Illinois. An engineer or surveyor must determine the elevation.
• Zone AH / AO – shallow flooding zones (1-3 ft of ponded water or sheet flow).
• Zone V / VE – coastal high-hazard areas with wave action. Coastal V and VE zones do not apply in Illinois because the state is inland.
• Zone X (shaded) – the 0.2% annual chance (500-year) floodplain. Insurance optional but risk is not zero.

Flood insurance in Illinois

If a Illinois property carries a federally backed mortgage and sits inside an SFHA zone (any A or V zone), flood insurance is mandatory. Properties outside the SFHA can buy NFIP coverage on a voluntary basis, often at a much lower premium. FEMA’s Risk Rating 2.0 system now prices NFIP premiums based on each individual property’s flood risk – distance to water, elevation, replacement cost – rather than zone alone, so two homes in the same zone can have very different premiums.

Frequently asked questions

What does “1% annual chance” mean for Illinois flood zones?

A 1% annual chance flood (the “100-year flood”) has a 1% probability of occurring in any single year. Over a 30-year mortgage, that compounds to roughly a 26% probability of at least one such flood at the property. SFHA zones in Illinois are defined by this 1% threshold.

How current are the Illinois flood maps shown here?

The polygons come from FEMA’s National Flood Hazard Layer, which FEMA updates on a rolling basis as individual communities complete new flood studies. Some Illinois communities have very recent maps; others may be running on FIRMs that are 10-20 years old. The effective date is shown in the FEMA Map Service Center for each panel.

Why is my Illinois property not in a flood zone but still flooded?

FEMA flood maps cover riverine and coastal flooding from named flood sources. They do not show pluvial (urban surface-water) flooding from extreme rainfall, sewer back-up, or drainage failure. A significant fraction of US flood losses each year happen outside mapped SFHAs – which is why FEMA encourages flood insurance even for Illinois properties in Zone X.

Flood zone maps for nearby states

• Indiana flood zones map
• Missouri flood zones map
• Iowa flood zones map
• Wisconsin flood zones map
• Kentucky flood zones map

Sources

• FEMA National Flood Hazard Layer – the source of all polygon geometry shown on the map.
• FEMA National Risk Index v1.20 (December 2025) – state and county expected annual loss figures.
• OpenFEMA Disaster Declarations Summaries – federal disaster declarations.
• FEMA Map Service Center – authoritative effective FIRM lookup.
• Mapscaping national FEMA Flood Zones map – the full US-wide version of this tool.