Mosquito season in Watonwan County, MN: when it starts and ends

Mosquito months in Watonwan County

In a normal year mosquito season in Watonwan County, MN starts around April 26 and ends around October 12, about 24 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 Watonwan County, and when

• Start tipping out standing water weekly by April 12.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 12.
• 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to July, more so if over 60.

Watonwan County against the rest of MN

Watonwan County has the 9th longest season of 87 MN counties, at 169 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 45.4°F.

• Rock County: April 25 to October 12 (170 days, 7 WNV)
• Hennepin County: April 25 to October 11 (169 days, 67 WNV)
• Brown County: April 26 to October 11 (168 days, 1 WNV)
• Houston County: April 27 to October 12 (168 days, 1 WNV)

West Nile in Watonwan County

From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Watonwan County (4 neuroinvasive) across 5 years. The worst was 2004 with 2; the latest was 2025.

See how the dates are worked out, and when mosquitoes go away for the winter.