Mosquito season in Genesee County, MI: when it starts and ends
Mosquito months in Genesee County
In a normal year mosquito season in Genesee County, MI starts around April 27 and ends around October 15, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Genesee 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 15.
- 9 West Nile cases since 2016 (last 2024): you should use repellent at dusk July to July, more so if over 60.
Genesee County against the rest of MI
Genesee County has the 28th longest season of 83 MI counties, at 171 days against 189 in Allegan County and 124 in Iron County. Its mean temperature is 47.5°F.
- Livingston County: April 26 to October 15 (172 days, 3 WNV)
- Washtenaw County: April 27 to October 16 (172 days, 3 WNV)
- Isabella County: April 27 to October 15 (171 days, 2 WNV)
- Midland County: April 27 to October 15 (171 days, 0 WNV)
West Nile in Genesee County
From 1999 to 2025, CDC ArboNET counted 16 human West Nile cases in Genesee County (14 neuroinvasive) across 10 years. The worst was 2024 with 3; the latest was 2024.
See how the dates are worked out, and reading the West Nile counts.