Mosquito season in Forest County, WI: when it starts and ends
Mosquito months in Forest County
In a normal year mosquito season in Forest County, WI starts around May 10 and ends around September 29, about 20 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Forest County, and when
- Start tipping out standing water weekly by April 26.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after September 29.
- No West Nile cases since 2016, so bites in Forest County are a nuisance; check window screens.
Forest County against the rest of WI
Forest County has the 68th longest season of 72 WI counties, at 141 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 40.1°F.
- Iron County: May 11 to September 30 (143 days, 0 WNV)
- Marinette County: May 14 to October 3 (142 days, 1 WNV)
- Florence County: May 11 to September 29 (141 days, 0 WNV)
- Oneida County: May 13 to October 1 (141 days, 0 WNV)
West Nile in Forest County
CDC ArboNET lists no human West Nile cases for Forest County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 6 of those years.
Background: when the season starts across the US; how the dates are worked out.