Janesville Average Temperature by Month

This page shows the average temperature in each month of the year in Janesville, Wisconsin. It is based on NOAA data for the years 1991–2020.
What's the Hottest Month in Janesville?
In Janesville, Wisconsin, the warmest month is July, with an average daily high temperature of 83.3 °F and an average low of 61.4 °F.
What's the Coldest Month in Janesville?
In Janesville, Wisconsin, the coolest month is January, with an average daily high temperature of 28.1 °F and an average low of 11.5 °F.
Month Avg. High Avg. Low
January 28.1 °F 11.5 °F
February 32.4 °F 14.4 °F
March 44.6 °F 25.1 °F
April 57.9 °F 35.8 °F
May 70.0 °F 47.7 °F
June 79.9 °F 57.7 °F
July 83.3 °F 61.4 °F
August 81.8 °F 59.4 °F
September 75.1 °F 50.8 °F
October 61.7 °F 39.3 °F
November 46.3 °F 28.3 °F
December 33.5 °F 18.1 °F
Year 58.0 °F 37.4 °F
Weather Station Details
Years Station Coordinates
1987–2024 Afton-Janesville WWTP location
1893–1987 Janesville location