Mosquito season in Knox County, OH: when it starts and ends
Mosquito months in Knox County
In a normal year mosquito season in Knox County, OH starts around April 21 and ends around October 17, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Knox County, and when
- Start tipping out standing water weekly by April 7.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 17.
- No West Nile cases since 2016, so bites in Knox County are a nuisance; check window screens.
Knox County against the rest of OH
Knox County has the 85th longest season of 88 OH counties, at 179 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 48.8°F.
- Medina County: April 21 to October 19 (181 days, 4 WNV)
- Trumbull County: April 22 to October 19 (180 days, 6 WNV)
- Portage County: April 22 to October 18 (179 days, 3 WNV)
- Geauga County: April 24 to October 18 (177 days, 0 WNV)
West Nile in Knox County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Knox County (3 neuroinvasive) across 3 years. The worst was 2013 with 1; the latest was 2013.
More: how the dates are worked out · when the season starts across the US.