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

Mosquito months in Kenosha County

In a normal year mosquito season in Kenosha County, WI starts around April 25 and ends around October 21, about 26 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Kenosha County, and when

• Start tipping out standing water weekly by April 11.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 21.
• 3 West Nile cases since 2016 (last 2024): you should use repellent at dusk July to August, more so if over 60.

Kenosha County against the rest of WI

Kenosha County has the 2nd longest season of 72 WI counties, at 179 days against 180 in La Crosse County and 139 in Rusk County. Its mean temperature is 48.8°F.

• La Crosse County: April 20 to October 17 (180 days, 3 WNV)
• Walworth County: April 23 to October 17 (177 days, 4 WNV)
• Rock County: April 23 to October 16 (176 days, 6 WNV)

West Nile in Kenosha County

From 1999 to 2025, CDC ArboNET counted 10 human West Nile cases in Kenosha County (6 neuroinvasive) across 6 years. The worst was 2012 with 3; the latest was 2024.

Background: when the season starts across the US; how the dates are worked out.