Mosquito season in Sanilac County, MI: when it starts and ends
Mosquito months in Sanilac County
In a normal year mosquito season in Sanilac County, MI starts around May 2 and ends around October 14, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sanilac County, and when
- Start tipping out standing water weekly by April 18.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 14.
- 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk July, more so if over 60.
Sanilac County against the rest of MI
Sanilac County has the 36th longest season of 83 MI counties, at 165 days against 189 in Allegan County and 124 in Iron County. Its mean temperature is 46.3°F.
- Manistee County: April 30 to October 17 (170 days, 0 WNV)
- Tuscola County: April 29 to October 14 (168 days, 4 WNV)
- Oceana County: May 2 to October 13 (164 days, 0 WNV)
- Benzie County: May 3 to October 14 (164 days, 0 WNV)
West Nile in Sanilac County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Sanilac County (5 neuroinvasive) across 4 years. The worst was 2025 with 2; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.