UV Index Today in Illinois (IL)

Friday, May 22, 2026 -1:37 PMCDT (GMT-5)

The average maximum UV Index today across 1,924 locations in Illinois (IL), is 4.3. The highest projected maximum is 7.5 in Fox Lake at 12:00 PM CDT, while the lowest projected maximum is 0.4 in Mount Vernon at 9:00 AM CDT.

Tomorrow, the average maximum UV Index across those same locations is expected to be 6.8. The highest projected maximum is 8.4 in Belleville at 1:00 PM CDT, and the lowest projected maximum is 4.4 in Mattoon at 12:00 PM CDT.

Data Source: National Oceanic and Atmospheric Administration (NOAA)

102 Counties in Illinois (IL)

Average Maximum UV Index Today
  • Cook County - 6.7
  • DuPage County - 6.8
  • Kane County - 6.9
  • Lake County - 6.7
  • McHenry County - 7.2
  • Madison County - 3.3
  • St. Clair County - 3.3
  • Will County - 6.9
  • Winnebago County - 6.7
Data Source: National Oceanic and Atmospheric Administration (NOAA)

935 Places in Illinois (IL)

Maximum UV Index Today
  • Chicago - 6.8
Data Source: National Oceanic and Atmospheric Administration (NOAA)