Mosquito season in Dane County, WI: when it starts and ends
Mosquito months in Dane County
In a normal year mosquito season in Dane County, WI starts around April 24 and ends around October 15, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Dane County, and when
- Start tipping out standing water weekly by April 10.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 15.
- 36 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to July, and check WI spray notices.
Dane County against the rest of WI
Dane County has the 8th longest season of 72 WI counties, at 174 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 47.1°F.
- Crawford County: April 23 to October 15 (175 days, 2 WNV)
- Green County: April 23 to October 15 (175 days, 1 WNV)
- Jefferson County: April 25 to October 16 (174 days, 7 WNV)
- Buffalo County: April 23 to October 13 (173 days, 1 WNV)
West Nile in Dane County
From 1999 to 2025, CDC ArboNET counted 60 human West Nile cases in Dane County (47 neuroinvasive) across 16 years. The worst was 2018 with 8; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.