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

Mosquito months in Waseca County

In a normal year mosquito season in Waseca County, MN starts around April 26 and ends around October 10, 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 Waseca 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 10.
• 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to July, more so if over 60.

Waseca County against the rest of MN

Waseca County has the 16th longest season of 87 MN counties, at 167 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 44.7°F.

• Nicollet County: April 26 to October 11 (167 days, 2 WNV)
• Sibley County: April 26 to October 11 (167 days, 6 WNV)
• Morrison County: April 27 to October 10 (167 days, 2 WNV)
• Washington County: April 27 to October 11 (167 days, 5 WNV)

West Nile in Waseca County

From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Waseca County (1 neuroinvasive) across 4 years. The worst was 2003 with 2; the latest was 2025.

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