Mosquito season in Monroe County, MI: when it starts and ends
Mosquito months in Monroe County
In a normal year mosquito season in Monroe County, MI starts around April 21 and ends around October 22, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Monroe County, and when
- Start tipping out standing water weekly by April 7.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 22.
- 7 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Monroe County against the rest of MI
Monroe County has the 4th longest season of 83 MI counties, at 184 days against 189 in Allegan County and 124 in Iron County. Its mean temperature is 49.8°F.
- Berrien County: April 18 to October 23 (188 days, 6 WNV)
- Van Buren County: April 22 to October 26 (187 days, 1 WNV)
- Kalamazoo County: April 19 to October 19 (183 days, 6 WNV)
- Wayne County: April 21 to October 21 (183 days, 110 WNV)
West Nile in Monroe County
From 1999 to 2025, CDC ArboNET counted 15 human West Nile cases in Monroe County (9 neuroinvasive) across 8 years. The worst was 2018 with 4; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.