Mosquito season in Western Connecticut Planning Region, CT: when it starts and ends
Mosquito months in Western Connecticut Planning Region
In a normal year mosquito season in Western Connecticut Planning Region, CT starts around April 19 and ends around October 22, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Western Connecticut Planning Region, and when
- Start tipping out standing water weekly by April 5.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 22.
- 10 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check CT spray notices.
Western Connecticut Planning Region against the rest of CT
Western Connecticut Planning Region has the 7th longest season of 9 CT counties, at 186 days against 200 in Greater Bridgeport Planning Region and 164 in Northwest Hills Planning Region. Its mean temperature is 50.4°F.
- Lower Connecticut River Valley Planning Region: April 17 to October 25 (191 days, 1 WNV)
- Naugatuck Valley Planning Region: April 20 to October 23 (187 days, 0 WNV)
- Northeastern Connecticut Planning Region: April 25 to October 17 (175 days, 0 WNV)
- Northwest Hills Planning Region: April 30 to October 11 (164 days, 0 WNV)
West Nile in Western Connecticut Planning Region
From 1999 to 2025, CDC ArboNET counted 10 human West Nile cases in Western Connecticut Planning Region (8 neuroinvasive) across 3 years. The worst was 2024 with 4; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.