Mosquito season in Lehigh County, PA: when it starts and ends
Mosquito months in Lehigh County
In a normal year mosquito season in Lehigh County, PA starts around April 13 and ends around October 25, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Lehigh County, and when
- Start tipping out standing water weekly by March 30.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 25.
- 13 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check PA spray notices.
Lehigh County against the rest of PA
Lehigh County has the 18th longest season of 67 PA counties, at 195 days against 222 in Philadelphia County and 154 in Clinton County. Its mean temperature is 51.8°F.
- Juniata County: April 13 to October 26 (196 days, 0 WNV)
- Northampton County: April 13 to October 26 (196 days, 4 WNV)
- Huntingdon County: April 14 to October 26 (195 days, 1 WNV)
- Perry County: April 14 to October 26 (195 days, 1 WNV)
West Nile in Lehigh County
From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in Lehigh County (16 neuroinvasive) across 8 years. The worst was 2018 with 4; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.