Mosquito season in Jefferson County, NY: when it starts and ends
Mosquito months in Jefferson County
In a normal year mosquito season in Jefferson County, NY starts around May 2 and ends around October 11, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Jefferson 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 11.
- 1 West Nile case since 2016 (last 2024): you should use repellent at dusk July, more so if over 60.
Jefferson County against the rest of NY
Jefferson County has the 43rd longest season of 62 NY counties, at 162 days against 218 in New York County and 125 in Franklin County. Its mean temperature is 45.3°F.
- Steuben County: May 1 to October 11 (163 days, 1 WNV)
- Clinton County: May 1 to October 10 (162 days, 2 WNV)
- Schuyler County: May 2 to October 11 (162 days, 0 WNV)
- Tioga County: May 2 to October 11 (162 days, 1 WNV)
West Nile in Jefferson County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Jefferson County (1 neuroinvasive) across 1 year. The worst was 2024 with 1; the latest was 2024.
More: how the dates are worked out · when the season starts across the US.