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Illinois heat wave risk

102 counties scored 1 rated Very High

Cook County has the highest heat wave risk in Illinois, scoring 99.8 out of 100 — rated "Very High" by FEMA's National Risk Index. Recorded heat wave events across Illinois have increased 66% over the past five years compared to the prior five-year period.

# County NRI score Rating NOAA events
2016–2026
1 Cook County 99.8 Very High 6
2 St. Clair County 98.1 Relatively High 14
3 Madison County 98 Relatively High 14
4 Sangamon County 96.2 Relatively Moderate 4
5 Will County 95.5 Relatively Moderate 7
6 Rock Island County 93.4 Relatively Moderate 0
7 DuPage County 93.3 Relatively Moderate 8
8 Peoria County 92.9 Relatively Moderate 5
9 Lake County 92.5 Relatively Moderate 5
10 Macoupin County 91.5 Relatively Moderate 5
11 Adams County 91.2 Relatively Moderate 6
12 Jackson County 90.7 Relatively Moderate 42
13 Williamson County 90.7 Relatively Moderate 47
14 Macon County 90.3 Relatively Moderate 3
15 Washington County 90.2 Relatively Moderate 8
16 Kane County 90 Relatively Moderate 7
17 Randolph County 89.2 Relatively Moderate 8
18 Champaign County 89.1 Relatively Moderate 3
19 Monroe County 87.6 Relatively Moderate 12
20 Franklin County 87.4 Relatively Moderate 41
21 Wayne County 86.4 Relatively Moderate 35
22 Tazewell County 86.1 Relatively Moderate 3
23 Winnebago County 85.3 Relatively Moderate 6
24 McLean County 85.2 Relatively Moderate 4
25 Union County 84.1 Relatively Moderate 46
26 Morgan County 83.4 Relatively Moderate 3
27 Marion County 83.3 Relatively Moderate 7
28 McDonough County 82.2 Relatively Moderate 0
29 Jefferson County 81.3 Relatively Moderate 40
30 Hancock County 80.4 Relatively Moderate 0
31 Knox County 80.3 Relatively Moderate 3
32 Montgomery County 79.4 Relatively Moderate 6
33 Jersey County 79.3 Relatively Moderate 7
34 Vermilion County 79.1 Relatively Moderate 3
35 Perry County 78.9 Relatively Moderate 40
36 Saline County 78.5 Relatively Low 40
37 Kankakee County 77.7 Relatively Low 7
38 Clinton County 77.2 Relatively Low 7
39 Pike County 77.2 Relatively Low 7
40 Fulton County 76.7 Relatively Low 3
41 McHenry County 75.5 Relatively Low 5
42 Logan County 75 Relatively Low 3
43 Massac County 72.8 Relatively Low 42
44 Gallatin County 71.6 Relatively Low 44
45 Fayette County 70.9 Relatively Low 5
46 Coles County 70.7 Relatively Low 2
47 Henry County 70.2 Relatively Low 0
48 LaSalle County 69.7 Relatively Low 9
49 Johnson County 68.9 Relatively Low 45
50 Christian County 68.2 Relatively Low 2
51 Effingham County 66.9 Relatively Low 2
52 Bond County 66 Relatively Low 5
53 Warren County 65.8 Relatively Low 0
54 White County 65.7 Relatively Low 40
55 Cass County 64.8 Relatively Low 3
56 Richland County 64.1 Relatively Low 2
57 Stephenson County 63.7 Relatively Low 0
58 Brown County 62.6 Relatively Low 4
59 Clay County 62.1 Relatively Low 3
60 Kendall County 61.9 Relatively Low 8
61 Greene County 61.8 Relatively Low 5
62 Menard County 60.1 Relatively Low 3
63 Calhoun County 59.6 Relatively Low 7
64 Edgar County 59.4 Relatively Low 3
65 DeKalb County 59 Relatively Low 7
66 Mason County 57.4 Relatively Low 3
67 Lawrence County 57.3 Relatively Low 2
68 Shelby County 56.3 Relatively Low 2
69 Moultrie County 55.8 Relatively Low 2
70 Crawford County 55.4 Relatively Low 2
71 Schuyler County 55.1 Relatively Low 3
72 Wabash County 54.5 Relatively Low 38
73 Douglas County 53.5 Relatively Low 2
74 Clark County 52.8 Relatively Low 2
75 Henderson County 52.2 Relatively Low 0
76 Pulaski County 50.6 Relatively Low 47
77 Alexander County 50.2 Relatively Low 46
78 Whiteside County 50.2 Relatively Low 0
79 Woodford County 49.4 Relatively Low 3
80 Livingston County 49.1 Relatively Low 11
81 Edwards County 49 Relatively Low 36
82 Jo Daviess County 48.7 Relatively Low 0
83 Mercer County 48.5 Relatively Low 0
84 Bureau County 48.2 Relatively Low 0
85 De Witt County 48.1 Relatively Low 3
86 Boone County 46.8 Relatively Low 6
87 Grundy County 45.9 Relatively Low 9
88 Hamilton County 44.1 Relatively Low 42
89 Iroquois County 44 Relatively Low 7
90 Cumberland County 43.9 Relatively Low 2
91 Piatt County 42.5 Relatively Low 3
92 Ogle County 41.7 Relatively Low 7
93 Jasper County 37.2 Very Low 2
94 Carroll County 36 Very Low 0
95 Scott County 35.1 Very Low 3
96 Marshall County 34.8 Very Low 3
97 Hardin County 34.5 Very Low 41
98 Pope County 34 Very Low 42
99 Lee County 31.9 Very Low 7
100 Ford County 31.3 Very Low 7
101 Stark County 22.6 Very Low 3
102 Putnam County 19.4 Very Low 0

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.

Heat Wave risk nationally:

Top 50 US counties

Other hazard risks in Illinois:

WildfireInland FloodingCoastal FloodingEarthquakeTornadoHurricaneHailStrong WindWinter WeatherIce StormCold WaveLightningDroughtLandslideAvalancheTsunamiVolcanic Activity

Frequently asked questions

What is the highest heat wave risk county in Illinois?

Cook County, IL has the highest heat wave risk in Illinois, with a FEMA National Risk Index score of 99.8 out of 100 (rated "Very High").

How many counties in Illinois are rated Very High for heat wave risk?

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

What causes heat wave risk in Illinois?

Heat is consistently the leading cause of weather-related mortality in the US, yet it remains underrepresented in federal disaster declarations relative to its actual impact. High scores reflect a combination of extreme temperature exposure, population vulnerability (elderly, outdoor workers), and limited access to cooling infrastructure.