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

Mosquito months in Cottonwood County

In a normal year mosquito season in Cottonwood County, MN starts around April 25 and ends around October 13, 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 Cottonwood 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 13.
• 7 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.

Cottonwood County against the rest of MN

Cottonwood County has the 5th longest season of 87 MN counties, at 171 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 45.9°F.

• Faribault County: April 24 to October 13 (172 days, 0 WNV)
• Ramsey County: April 24 to October 13 (172 days, 20 WNV)
• Martin County: April 25 to October 13 (171 days, 6 WNV)
• Rock County: April 25 to October 12 (170 days, 7 WNV)

West Nile in Cottonwood County

From 1999 to 2025, CDC ArboNET counted 18 human West Nile cases in Cottonwood County (8 neuroinvasive) across 8 years. The worst was 2003 with 5; the latest was 2025.

See how the dates are worked out, and reading the West Nile counts.