Mosquito season in Lyon County, MN: when it starts and ends
Mosquito months in Lyon County
In a normal year mosquito season in Lyon County, MN starts around April 27 and ends around October 11, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Lyon 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 11.
- 18 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check MN spray notices.
Lyon County against the rest of MN
Lyon County has the 20th longest season of 87 MN counties, at 166 days against 176 in Winona County and 118 in Cook County. Its mean temperature is 45°F.
- Washington County: April 27 to October 11 (167 days, 5 WNV)
- Steele County: April 28 to October 11 (167 days, 3 WNV)
- Redwood County: April 27 to October 10 (166 days, 9 WNV)
- Chippewa County: April 27 to October 10 (165 days, 3 WNV)
West Nile in Lyon County
From 1999 to 2025, CDC ArboNET counted 35 human West Nile cases in Lyon County (10 neuroinvasive) across 14 years. The worst was 2025 with 6; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.