Mosquito season in Blair County, PA: when it starts and ends
Mosquito months in Blair County
In a normal year mosquito season in Blair County, PA starts around April 17 and ends around October 21, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Blair County, and when
- Start tipping out standing water weekly by April 3.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 21.
- 1 West Nile case since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Blair County against the rest of PA
Blair County has the 25th longest season of 67 PA counties, at 188 days against 222 in Philadelphia County and 154 in Clinton County. Its mean temperature is 50.2°F.
- Mifflin County: April 16 to October 22 (190 days, 0 WNV)
- Beaver County: April 17 to October 23 (189 days, 3 WNV)
- Dauphin County: April 18 to October 23 (188 days, 8 WNV)
- Lawrence County: April 20 to October 25 (188 days, 2 WNV)
West Nile in Blair County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Blair County (0 neuroinvasive) across 1 year. The worst was 2025 with 1; the latest was 2025.
See how the dates are worked out, and when the season starts across the US.