Mosquito season in Sullivan County, PA: when it starts and ends
Mosquito months in Sullivan County
In a normal year mosquito season in Sullivan County, PA starts around May 2 and ends around October 8, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sullivan County, and when
- Start tipping out standing water weekly by April 18.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 8.
- No West Nile cases since 2016, so bites in Sullivan County are a nuisance; check window screens.
Sullivan County against the rest of PA
Sullivan County has the 63rd longest season of 67 PA counties, at 158 days against 222 in Philadelphia County and 154 in Clinton County. Its mean temperature is 45.1°F.
- Wayne County: May 3 to October 10 (160 days, 0 WNV)
- Susquehanna County: May 3 to October 9 (159 days, 0 WNV)
- Potter County: May 3 to October 8 (158 days, 1 WNV)
- Fayette County: May 5 to October 10 (158 days, 3 WNV)
West Nile in Sullivan County
CDC ArboNET lists no human West Nile cases for Sullivan County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 5 of those years.
More: how the dates are worked out · when the season starts across the US.