Mosquito season in Chittenden County, VT: when it starts and ends
Mosquito months in Chittenden County
In a normal year mosquito season in Chittenden County, VT starts around April 27 and ends around October 14, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Chittenden County, and when
- Start tipping out standing water weekly by April 13.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 14.
- 2 West Nile cases since 2016 (last 2024): you should use repellent at dusk July to August, more so if over 60.
Chittenden County against the rest of VT
Chittenden County has the 1st longest season of 14 VT counties, at 171 days against 171 in Chittenden County and 144 in Orleans County. Its mean temperature is 46.9°F.
- Grand Isle County: April 27 to October 15 (171 days, 2 WNV)
- Addison County: April 30 to October 11 (164 days, 1 WNV)
West Nile in Chittenden County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Chittenden County (3 neuroinvasive) across 3 years. The worst was 2024 with 1; the latest was 2024.
More: how the dates are worked out · when mosquitoes go away for the winter.