UV Index Today in St. Charles County, Missouri (MO)

The average maximum UV Index today across 35 locations in St. Charles County, Missouri (MO), is 9.4. The highest projected maximum is 10.1 in Alton at 1:00 PM CDT, while the lowest projected maximum is 9.3 in O'Fallon at 12:00 PM CDT.

Tomorrow, the average maximum UV Index across those same locations is expected to be 9.8. The highest projected maximum is 10 in Alton at 1:00 PM CDT, and the lowest projected maximum is 9.3 in Florissant at 12:00 PM CDT.