Mosquito season in Williams County, OH: when it starts and ends
Mosquito months in Williams County
In a normal year mosquito season in Williams County, OH starts around April 21 and ends around October 20, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Williams 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 20.
- 1 West Nile case since 2016 (last 2018): you should use repellent at dusk July to August, more so if over 60.
Williams County against the rest of OH
Williams County has the 81st longest season of 88 OH counties, at 182 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 49.2°F.
- Mahoning County: April 20 to October 20 (183 days, 3 WNV)
- Holmes County: April 21 to October 21 (183 days, 3 WNV)
- Fulton County: April 21 to October 19 (181 days, 3 WNV)
- Medina County: April 21 to October 19 (181 days, 4 WNV)
West Nile in Williams County
From 1999 to 2025, CDC ArboNET counted 8 human West Nile cases in Williams County (5 neuroinvasive) across 5 years. The worst was 2015 with 4; the latest was 2018.
Background: when the season starts across the US; how the dates are worked out.