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

Mosquito months in Ramsey County

In a normal year mosquito season in Ramsey County, MN starts around April 24 and ends around October 13, about 25 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 Ramsey County, and when

• Start tipping out standing water weekly by April 10.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 13.
• 20 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check MN spray notices.

Ramsey County against the rest of MN

Ramsey County has the 4th longest season of 87 MN counties, at 172 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 46.1°F.

• Blue Earth County: April 23 to October 14 (173 days, 9 WNV)
• Faribault County: April 24 to October 13 (172 days, 0 WNV)
• Cottonwood County: April 25 to October 13 (171 days, 7 WNV)
• Martin County: April 25 to October 13 (171 days, 6 WNV)

West Nile in Ramsey County

From 1999 to 2025, CDC ArboNET counted 46 human West Nile cases in Ramsey County (27 neuroinvasive) across 17 years. The worst was 2006 with 5; the latest was 2025.

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