Charleston Average Temperature by Month

This page shows the average temperature in each month of the year in Charleston, Illinois. It is based on NOAA data for the years 1991–2020.
What's the Hottest Month in Charleston?
In Charleston, Illinois, the warmest month is July, with an average daily high temperature of 86.9 °F and an average low of 66.3 °F.
What's the Coldest Month in Charleston?
In Charleston, Illinois, the coolest month is January, with an average daily high temperature of 37.1 °F and an average low of 21.1 °F.
Month Avg. High Avg. Low
January 37.1 °F 21.1 °F
February 42.0 °F 24.4 °F
March 53.7 °F 33.7 °F
April 66.7 °F 44.2 °F
May 76.0 °F 54.4 °F
June 84.4 °F 63.0 °F
July 86.9 °F 66.3 °F
August 85.9 °F 64.4 °F
September 80.1 °F 56.5 °F
October 67.6 °F 45.5 °F
November 53.8 °F 35.3 °F
December 41.5 °F 25.9 °F
Year 64.8 °F 44.8 °F
Weather Station Details
Years Station Coordinates
1896–2024 Charleston location
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