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Illinois inland flooding risk

102 counties scored 1 rated Very High

Cook County has the highest inland flooding risk in Illinois, scoring 99.9 out of 100 — rated "Very High" by FEMA's National Risk Index. Recorded inland flooding events across Illinois have decreased 41% over the past five years compared to the prior five-year period.

# County NRI score Rating NOAA events
2016–2026
1 Cook County 99.9 Very High 221
2 DuPage County 98 Relatively High 76
3 Will County 97.9 Relatively High 63
4 Lake County 97.2 Relatively High 37
5 Kane County 95.5 Relatively High 20
6 St. Clair County 94.5 Relatively High 17
7 Winnebago County 94.4 Relatively High 40
8 McHenry County 93.1 Relatively Moderate 18
9 Kankakee County 92.5 Relatively Moderate 21
10 Madison County 92.3 Relatively Moderate 5
11 Sangamon County 91.2 Relatively Moderate 35
12 Champaign County 90.4 Relatively Moderate 26
13 Peoria County 88.7 Relatively Moderate 17
14 LaSalle County 88.2 Relatively Moderate 22
15 McLean County 85.2 Relatively Moderate 19
16 Tazewell County 84.4 Relatively Moderate 19
17 Macon County 83.3 Relatively Moderate 13
18 DeKalb County 83 Relatively Moderate 12
19 Livingston County 81.1 Relatively Moderate 17
20 Kendall County 79.7 Relatively Moderate 16
21 Iroquois County 79.6 Relatively Moderate 17
22 Rock Island County 79.5 Relatively Moderate 49
23 Stephenson County 77.9 Relatively Moderate 22
24 Ogle County 77 Relatively Moderate 19
25 Jackson County 76.5 Relatively Moderate 58
26 Vermilion County 76.5 Relatively Moderate 13
27 Coles County 74.5 Relatively Moderate 14
28 Whiteside County 70.1 Relatively Low 20
29 Williamson County 69.9 Relatively Low 27
30 Macoupin County 68.7 Relatively Low 3
31 Marion County 68.1 Relatively Low 10
32 Grundy County 66.5 Relatively Low 13
33 Franklin County 65.7 Relatively Low 48
34 Clinton County 64 Relatively Low 4
35 Boone County 63.9 Relatively Low 16
36 Bureau County 63.4 Relatively Low 16
37 Lee County 62.5 Relatively Low 11
38 Morgan County 61.2 Relatively Low 11
39 Adams County 60.7 Relatively Low 7
40 Douglas County 60.1 Relatively Low 9
41 Jefferson County 59 Relatively Low 19
42 Montgomery County 58.7 Relatively Low 7
43 Jo Daviess County 58.5 Relatively Low 21
44 Lawrence County 58.2 Relatively Low 18
45 Randolph County 57.8 Relatively Low 9
46 Fulton County 57.6 Relatively Low 14
47 Saline County 57.4 Relatively Low 19
48 Logan County 53.7 Relatively Low 9
49 Henry County 51.5 Relatively Low 13
50 Woodford County 51.5 Relatively Low 13
51 Perry County 49.8 Relatively Low 28
52 Fayette County 49.5 Relatively Low 4
53 Knox County 49.4 Relatively Low 6
54 Effingham County 49.2 Relatively Low 25
55 Moultrie County 49.1 Relatively Low 8
56 Shelby County 48.3 Relatively Low 23
57 Mason County 47.2 Relatively Low 5
58 Carroll County 46.5 Relatively Low 15
59 White County 44.3 Relatively Low 82
60 Crawford County 43.7 Relatively Low 19
61 Piatt County 43.7 Relatively Low 5
62 Massac County 43 Relatively Low 35
63 Christian County 41.5 Relatively Low 17
64 Richland County 41.3 Relatively Low 12
65 Alexander County 40.5 Relatively Low 80
66 Washington County 39 Relatively Low 4
67 Clay County 38.9 Relatively Low 27
68 Union County 38.9 Relatively Low 16
69 Johnson County 37.9 Relatively Low 5
70 Gallatin County 36 Relatively Low 51
71 Ford County 35.6 Relatively Low 13
72 Wayne County 35.4 Relatively Low 40
73 Marshall County 35.1 Relatively Low 7
74 Pike County 33.7 Very Low 3
75 Cumberland County 33.5 Very Low 11
76 Monroe County 32.3 Very Low 6
77 Clark County 31 Very Low 8
78 Bond County 30.5 Very Low 3
79 De Witt County 30.3 Very Low 3
80 Edgar County 30 Very Low 10
81 Menard County 29.4 Very Low 6
82 Jasper County 28.4 Very Low 11
83 Cass County 28.1 Very Low 6
84 Wabash County 25.8 Very Low 40
85 Henderson County 24.7 Very Low 19
86 Hancock County 24.2 Very Low 15
87 Edwards County 21.5 Very Low 8
88 McDonough County 21.1 Very Low 17
89 Putnam County 19.6 Very Low 3
90 Jersey County 18 Very Low 2
91 Pope County 17.2 Very Low 22
92 Calhoun County 16.1 Very Low 2
93 Hardin County 15.5 Very Low 15
94 Pulaski County 15.1 Very Low 40
95 Greene County 13.2 Very Low 3
96 Hamilton County 12.5 Very Low 23
97 Stark County 11.2 Very Low 2
98 Warren County 11 Very Low 4
99 Mercer County 9.2 Very Low 20
100 Schuyler County 8.2 Very Low 6
101 Scott County 5.1 Very Low 5
102 Brown County 4.1 Very Low 1

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.

Inland Flooding risk nationally:

Top 50 US counties

Other hazard risks in Illinois:

WildfireCoastal FloodingEarthquakeHeat WaveTornadoHurricaneHailStrong WindWinter WeatherIce StormCold WaveLightningDroughtLandslideAvalancheTsunamiVolcanic Activity

Frequently asked questions

What is the highest inland flooding risk county in Illinois?

Cook County, IL has the highest inland flooding risk in Illinois, with a FEMA National Risk Index score of 99.9 out of 100 (rated "Very High").

How many counties in Illinois are rated Very High for inland flooding risk?

1 of 102 scored Illinois counties are rated "Very High" for inland flooding risk by FEMA's National Risk Index.

What causes inland flooding risk in Illinois?

Inland flooding covers riverine and surface (pluvial) flooding — the most common and costly natural disaster type in the US. High scores appear across river floodplains in the Midwest, South, and Mid-Atlantic, where legacy development in flood-prone areas and aging stormwater infrastructure concentrate risk.