15,260 flood insurance claims·$139.3M paid·8 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Cook County, Illinois. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flash flooding and river flooding from summer thunderstorms dominate Cook County, with 206 flood events and 184 flash flood events recorded over the last 30 years, alongside 3 lakeshore flood events.
Recent impacts are documented in NOAA storm narratives. On July 25, 2025, a narrow line of thunderstorms produced torrential rainfall and widespread flash flooding across central Cook Counties. Subsequently, a series of thunderstorms on August 17, 2025, brought widespread flooding to the Chicago metro area, south and west suburbs, and the city of Chicago, resulting in roughly $288 million in estimated damages across the metro area, about $230 million in damages within Chicago alone, and approximately 40,000 flooded structures.
Residents and property owners should pay the closest attention based on their National Flood Insurance Program zone classifications. High-risk Zone A properties have recorded the highest claim volume with 10,008 claims, averaging $12,825 per payout and an average recorded water depth of 10 inches. However, properties in Zone X are also vulnerable, accounting for 2,669 claims with an average payout of $15,474 and an average recorded water depth of 11 inches. Additional claims are distributed across Zone X shaded, Zone X unshaded, and unknown zones, indicating that flood risk extends beyond designated high-risk areas.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
16% of Cook County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
11,885 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 10 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 2008, with 2,048 claims and $33.7M paid, the year of Severe Storms and Flooding.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
125 NOAA storm reports from Cook County describe what happened, in the words of the forecasters who covered it. Read the Illinois flood stories →
24 federal disaster declarations since 1967, 8 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storms, Tornadoes, Straight-line Winds, And Floodng | Jul 13, 2024 |
| Severe Storms And Flooding | Sep 17, 2023 |
| Severe Storms And Flooding | Jun 29, 2023 |
| Severe Storms, Straight-line Winds, And Flooding | Apr 16, 2013 |
| Severe Winter Storm And Snowstorm | Jan 31, 2011 |
| Severe Storms And Flooding | Jul 19, 2010 |
| Severe Storms And Flooding | Sep 13, 2008 |
| Severe Storms And Flooding | Aug 20, 2007 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
393 since 1996: 184 flash floods, 206 river or area floods and 3 coastal floods or surges.
| Event | Date | Damage |
|---|---|---|
| Flood | Jan 31, 2025 | — |
| Flood | Jul 28, 2025 | — |
| Flood | Jul 25, 2025 | — |
| Flash Flood | Jul 25, 2025 | $200.0M |
| Flood | Jul 24, 2025 | — |
| Flash Flood | Jul 24, 2025 | — |
| Flood | Jun 18, 2025 | — |
| Flash Flood | Aug 18, 2025 | $1.5M |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · Jan 31, 2025. Persistent moderate to heavy rain during the morning of the 31st resulted in a few instances of localized flooding, mainly around the interior Chicago metro area. Despite rain reports largely below 1.5, NWS Chicago recorded a 12 frost depth in Romeoville on the morning of the 31st, which made the area more susceptible to flooding.
Flood · Jul 28, 2025. Isolated thunderstorms moved across portions of northeast Illinois during the afternoon of July 28th.
Flood · Jul 25, 2025. Isolated thunderstorms produced funnel clouds across central Illinois during the late morning of July 25th. A narrow line of thunderstorms developed over southeast DuPage and central Cook Counties during the late morning of July 25th and continued into the early afternoon producing torrential rainfall and widespread flash flooding. Scattered thunderstorms moved across portions of northern Illinois during the lat…
Flash Flood · Jul 25, 2025. Isolated thunderstorms produced funnel clouds across central Illinois during the late morning of July 25th. A narrow line of thunderstorms developed over southeast DuPage and central Cook Counties during the late morning of July 25th and continued into the early afternoon producing torrential rainfall and widespread flash flooding. Scattered thunderstorms moved across portions of northern Illinois during the lat…
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Cook County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.