June in Janesville averages a daily high of 26.7°C with nights around 14.5°C. Expect roughly 12.5 wet days totalling 124.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Janesville is May–September.
Based on AFTON JANESVILLE WWTP, WI US (6.3km), 1995–2024. 29 years of June data.