Mosquito season in Essex County, MA: when it starts and ends
Mosquito months in Essex County
In a normal year mosquito season in Essex County, MA starts around April 28 and ends around October 19, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Essex County, and when
- Start tipping out standing water weekly by April 14.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 19.
- 14 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to July, and check MA spray notices.
Essex County against the rest of MA
Essex County has the 12th longest season of 14 MA counties, at 174 days against 194 in Plymouth County and 163 in Berkshire County. Its mean temperature is 48.8°F.
- Hampshire County: April 24 to October 16 (175 days, 2 WNV)
- Franklin County: April 25 to October 16 (174 days, 2 WNV)
- Worcester County: April 26 to October 16 (172 days, 7 WNV)
- Berkshire County: April 30 to October 10 (163 days, 1 WNV)
West Nile in Essex County
From 1999 to 2025, CDC ArboNET counted 21 human West Nile cases in Essex County (17 neuroinvasive) across 10 years. The worst was 2018 with 8; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.