Mosquito season in Chisago County, MN: when it starts and ends
Mosquito months in Chisago County
In a normal year mosquito season in Chisago County, MN starts around May 6 and ends around October 4, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Chisago County, and when
- Start tipping out standing water weekly by April 22.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 4.
- 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to July, more so if over 60.
Chisago County against the rest of MN
Chisago County has the 65th longest season of 87 MN counties, at 151 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 43.4°F.
- Becker County: May 5 to October 3 (151 days, 5 WNV)
- Otter Tail County: May 5 to October 3 (151 days, 9 WNV)
- Norman County: May 5 to October 2 (150 days, 3 WNV)
- Mahnomen County: May 5 to October 2 (149 days, 0 WNV)
West Nile in Chisago County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Chisago County (3 neuroinvasive) across 4 years. The worst was 2006 with 2; the latest was 2025.
See how the dates are worked out, and when the season starts across the US.