Mosquito season in York County, PA: when it starts and ends
Mosquito months in York County
In a normal year mosquito season in York County, PA starts around April 8 and ends around October 30, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in York County, and when
- Start tipping out standing water weekly by March 25.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 30.
- 14 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check PA spray notices.
York County against the rest of PA
York County has the 4th longest season of 67 PA counties, at 205 days against 222 in Philadelphia County and 154 in Clinton County. Its mean temperature is 53.6°F.
- Delaware County: April 4 to November 7 (217 days, 24 WNV)
- Berks County: April 9 to October 31 (206 days, 17 WNV)
- Lancaster County: April 9 to October 29 (204 days, 44 WNV)
- Bucks County: April 10 to October 31 (204 days, 28 WNV)
West Nile in York County
From 1999 to 2025, CDC ArboNET counted 52 human West Nile cases in York County (33 neuroinvasive) across 16 years. The worst was 2003 with 16; the latest was 2025.
Background: reading the West Nile counts; how the dates are worked out.