Mosquito season in Ulster County, NY: when it starts and ends
Mosquito months in Ulster County
In a normal year mosquito season in Ulster County, NY starts around April 20 and ends around October 20, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Ulster County, and when
- Start tipping out standing water weekly by April 6.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 20.
- 2 West Nile cases since 2016 (last 2018): you should use repellent at dusk July to August, more so if over 60.
Ulster County against the rest of NY
Ulster County has the 12th longest season of 62 NY counties, at 183 days against 218 in New York County and 125 in Franklin County. Its mean temperature is 49.7°F.
- Putnam County: April 19 to October 21 (184 days, 0 WNV)
- Orange County: April 20 to October 20 (183 days, 0 WNV)
- Chautauqua County: April 23 to October 23 (183 days, 0 WNV)
- Orleans County: April 24 to October 21 (180 days, 1 WNV)
West Nile in Ulster County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Ulster County (1 neuroinvasive) across 2 years. The worst was 2018 with 2; the latest was 2018.
Background: when mosquitoes go away for the winter; how the dates are worked out.