Mosquito season in Hardin County, OH: when it starts and ends
Mosquito months in Hardin County
In a normal year mosquito season in Hardin 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 Hardin 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.
- 2 West Nile cases since 2016 (last 2021): you should use repellent at dusk June to August, more so if over 60.
Hardin County against the rest of OH
Hardin County has the 50th longest season of 88 OH counties, at 191 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 50.9°F.
- Erie County: April 18 to October 27 (192 days, 1 WNV)
- Madison County: April 14 to October 22 (191 days, 0 WNV)
- Shelby County: April 16 to October 24 (191 days, 0 WNV)
- Ottawa County: April 17 to October 26 (191 days, 1 WNV)
West Nile in Hardin County
From 1999 to 2025, CDC ArboNET counted 5 human West Nile cases in Hardin County (2 neuroinvasive) across 4 years. The worst was 2002 with 2; the latest was 2021.
More: how the dates are worked out · when the season starts across the US.