Illinois coastal flooding risk
Cook County has the highest coastal flooding risk in Illinois, scoring 44 out of 100 — rated "Relatively Low" by FEMA's National Risk Index.
| # | County | NRI score | Rating |
|---|---|---|---|
| 1 | Cook County | 44 | Relatively Low |
| 2 | Lake County | 29.8 | Very Low |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Coastal Flooding risk nationally:
Other hazard risks in Illinois:
Frequently asked questions
What is the highest coastal flooding risk county in Illinois?
Cook County, IL has the highest coastal flooding risk in Illinois, with a FEMA National Risk Index score of 44 out of 100 (rated "Relatively Low").
What causes coastal flooding risk in Illinois?
Coastal flooding scores cover storm surge, wave action, and tidal flooding along the Gulf, Atlantic, and Pacific coasts, and Great Lakes shoreline. Inland flooding is scored separately. Counties with "Not Applicable" ratings have no significant coastal exposure. Coastal flood events are reported at zone level in NOAA Storm Events and are not included in county-level counts.