Mosquito season in Shelby County, OH: when it starts and ends
Mosquito months in Shelby County
In a normal year mosquito season in Shelby County, OH starts around April 16 and ends around October 24, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Shelby County, and when
- Start tipping out standing water weekly by April 2.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 24.
- No West Nile cases since 2016, so bites in Shelby County are a nuisance; check window screens.
Shelby County against the rest of OH
Shelby County has the 51st longest season of 88 OH counties, at 191 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 51.2°F.
- Madison County: April 14 to October 22 (191 days, 0 WNV)
- Hardin County: April 16 to October 24 (191 days, 2 WNV)
- Ottawa County: April 17 to October 26 (191 days, 1 WNV)
- Logan County: April 16 to October 23 (190 days, 2 WNV)
West Nile in Shelby County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Shelby County (1 neuroinvasive) across 2 years. The worst was 2004 with 1; the latest was 2004.
Background: when mosquitoes go away for the winter; how the dates are worked out.