Mosquito season in Portage County, OH: when it starts and ends
Mosquito months in Portage County
In a normal year mosquito season in Portage County, OH starts around April 22 and ends around October 18, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Portage County, and when
- Start tipping out standing water weekly by April 8.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 18.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to July, more so if over 60.
Portage County against the rest of OH
Portage County has the 86th longest season of 88 OH counties, at 179 days against 209 in Gallia County and 177 in Ashtabula County. Its mean temperature is 49°F.
- Trumbull County: April 22 to October 19 (180 days, 6 WNV)
- Knox County: April 21 to October 17 (179 days, 0 WNV)
- Geauga County: April 24 to October 18 (177 days, 0 WNV)
- Ashtabula County: April 25 to October 19 (177 days, 3 WNV)
West Nile in Portage County
From 1999 to 2025, CDC ArboNET counted 6 human West Nile cases in Portage County (5 neuroinvasive) across 5 years. The worst was 2025 with 2; the latest was 2025.
More: how the dates are worked out · when the season starts across the US.