Mosquito season in Green Lake County, WI: when it starts and ends

Mosquito months in Green Lake County

In a normal year mosquito season in Green Lake County, WI starts around April 29 and ends around October 11, about 24 weeks.

What to do in Green Lake County, and when

Start tipping out standing water weekly by April 15.
Book any yard treatment for late April, ahead of the July peak.
Repellent can go away after October 11.
No West Nile cases since 2016, so bites in Green Lake County are a nuisance; check window screens.

Green Lake County against the rest of WI

Green Lake County has the 24th longest season of 72 WI counties, at 165 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 45.3°F.

Sheboygan County: May 3 to October 17 (166 days, 3 WNV)
Dodge County: April 29 to October 11 (165 days, 1 WNV)
Calumet County: April 30 to October 12 (165 days, 3 WNV)
Washington County: May 1 to October 12 (165 days, 2 WNV)

West Nile in Green Lake County

CDC ArboNET lists no human West Nile cases for Green Lake County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 9 of those years.

More: how the dates are worked out · when the season starts across the US.