Mosquito season in Suffolk County, MA: when it starts and ends
Mosquito months in Suffolk County
In a normal year mosquito season in Suffolk County, MA starts around April 19 and ends around October 29, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Suffolk County, 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 29.
- 18 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check MA spray notices.
Suffolk County against the rest of MA
Suffolk County has the 2nd longest season of 14 MA counties, at 193 days against 194 in Plymouth County and 163 in Berkshire County. Its mean temperature is 51.9°F.
- Plymouth County: April 20 to October 31 (194 days, 5 WNV)
- Norfolk County: April 15 to October 23 (191 days, 6 WNV)
- Nantucket County: May 1 to November 2 (185 days, 0 WNV)
West Nile in Suffolk County
From 1999 to 2025, CDC ArboNET counted 45 human West Nile cases in Suffolk County (39 neuroinvasive) across 13 years. The worst was 2018 with 9; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.