Mosquito season in Vernon County, WI: when it starts and ends
Mosquito months in Vernon County
In a normal year mosquito season in Vernon County, WI starts around April 30 and ends around October 8, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Vernon County, and when
- Start tipping out standing water weekly by April 16.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 8.
- No West Nile cases since 2016, so bites in Vernon County are a nuisance; check window screens.
Vernon County against the rest of WI
Vernon County has the 41st longest season of 72 WI counties, at 160 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 44°F.
- Wood County: April 30 to October 8 (161 days, 5 WNV)
- Jackson County: April 30 to October 7 (160 days, 0 WNV)
- Portage County: May 1 to October 8 (160 days, 1 WNV)
- Ozaukee County: May 6 to October 12 (160 days, 2 WNV)
West Nile in Vernon County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Vernon County (0 neuroinvasive) across 1 year. The worst was 2003 with 1; the latest was 2003.
More: how the dates are worked out · when mosquitoes go away for the winter.