Mosquito season in Harrison County, OH: when it starts and ends
Mosquito months in Harrison County
In a normal year mosquito season in Harrison County, OH starts around April 14 and ends around October 23, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Harrison 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 23.
- No West Nile cases since 2016, so bites in Harrison County are a nuisance; check window screens.
Harrison County against the rest of OH
Harrison County has the 41st longest season of 88 OH counties, at 192 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 50.9°F.
- Lorain County: April 16 to October 26 (193 days, 3 WNV)
- Champaign County: April 14 to October 23 (192 days, 0 WNV)
- Clark County: April 15 to October 24 (192 days, 5 WNV)
- Coshocton County: April 15 to October 24 (192 days, 0 WNV)
West Nile in Harrison County
CDC ArboNET lists no human West Nile cases for Harrison County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 3 of those years.
Background: when the season starts across the US; how the dates are worked out.