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

Mosquito months in Isanti County

In a normal year mosquito season in Isanti County, MN starts around April 27 and ends around October 9, 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 Isanti County, and when

• Start tipping out standing water weekly by April 13.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 9.
• 1 West Nile case since 2016 (last 2016): you should use repellent at dusk July to July, more so if over 60.

Isanti County against the rest of MN

Isanti County has the 23rd longest season of 87 MN counties, at 165 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 44.1°F.

• Redwood County: April 27 to October 10 (166 days, 9 WNV)
• Chippewa County: April 27 to October 10 (165 days, 3 WNV)
• McLeod County: April 27 to October 10 (165 days, 4 WNV)
• Scott County: April 28 to October 10 (165 days, 13 WNV)

West Nile in Isanti County

From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Isanti County (1 neuroinvasive) across 6 years. The worst was 2016 with 1; the latest was 2016.

See how the dates are worked out, and when the season starts across the US.