Mosquito season in Ionia County, MI: when it starts and ends
Mosquito months in Ionia County
In a normal year mosquito season in Ionia County, MI starts around April 27 and ends around October 13, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Ionia 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 13.
- 2 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to July, more so if over 60.
Ionia County against the rest of MI
Ionia County has the 33rd longest season of 83 MI counties, at 170 days against 189 in Allegan County and 124 in Iron County. Its mean temperature is 47.1°F.
- Bay County: April 28 to October 16 (171 days, 4 WNV)
- Gratiot County: April 27 to October 14 (170 days, 1 WNV)
- Manistee County: April 30 to October 17 (170 days, 0 WNV)
- Tuscola County: April 29 to October 14 (168 days, 4 WNV)
West Nile in Ionia County
From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Ionia County (2 neuroinvasive) across 2 years. The worst was 2025 with 2; the latest was 2025.
See how the dates are worked out, and when mosquitoes go away for the winter.