Mosquito season in Clinton County, MI: when it starts and ends

Mosquito months in Clinton County

In a normal year mosquito season in Clinton County, MI starts around April 23 and ends around October 20, about 26 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Clinton County, and when

• Start tipping out standing water weekly by April 9.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 20.
• 4 West Nile cases since 2016 (last 2023): you should use repellent at dusk July to August, more so if over 60.

Clinton County against the rest of MI

Clinton County has the 10th longest season of 83 MI counties, at 180 days against 189 in Allegan County and 124 in Iron County. Its mean temperature is 49°F.

• Calhoun County: April 21 to October 19 (181 days, 3 WNV)
• Jackson County: April 21 to October 18 (180 days, 3 WNV)
• Ingham County: April 22 to October 18 (179 days, 12 WNV)
• St. Joseph County: April 22 to October 18 (179 days, 3 WNV)

West Nile in Clinton County

From 1999 to 2025, CDC ArboNET counted 10 human West Nile cases in Clinton County (8 neuroinvasive) across 6 years. The worst was 2020 with 2; the latest was 2023.

Background: reading the West Nile counts; how the dates are worked out.