Mosquito season in Madison County, OH: when it starts and ends
Mosquito months in Madison County
In a normal year mosquito season in Madison County, OH starts around April 14 and ends around October 22, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Madison County, and when
- Start tipping out standing water weekly by March 31.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 22.
- No West Nile cases since 2016, so bites in Madison County are a nuisance; check window screens.
Madison County against the rest of OH
Madison County has the 49th longest season of 88 OH counties, at 191 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 50.8°F.
- Van Wert County: April 16 to October 24 (192 days, 1 WNV)
- Erie County: April 18 to October 27 (192 days, 1 WNV)
- Hardin County: April 16 to October 24 (191 days, 2 WNV)
- Shelby County: April 16 to October 24 (191 days, 0 WNV)
West Nile in Madison County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Madison County (2 neuroinvasive) across 1 year. The worst was 2002 with 3; the latest was 2002.
See how the dates are worked out, and when mosquitoes go away for the winter.