Mosquito season in Franklin County, MA: when it starts and ends
Mosquito months in Franklin County
In a normal year mosquito season in Franklin County, MA starts around April 25 and ends around October 16, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Franklin County, and when
- Start tipping out standing water weekly by April 11.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 16.
- 2 West Nile cases since 2016 (last 2018): you should use repellent at dusk July to July, more so if over 60.
Franklin County against the rest of MA
Franklin County has the 11th longest season of 14 MA counties, at 174 days against 194 in Plymouth County and 163 in Berkshire County. Its mean temperature is 47.9°F.
- Middlesex County: April 21 to October 18 (180 days, 65 WNV)
- Hampshire County: April 24 to October 16 (175 days, 2 WNV)
- Essex County: April 28 to October 19 (174 days, 14 WNV)
- Worcester County: April 26 to October 16 (172 days, 7 WNV)
West Nile in Franklin County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Franklin County (1 neuroinvasive) across 2 years. The worst was 2018 with 1; the latest was 2018.
See how the dates are worked out, and when the season starts across the US.