Mosquito season in Hampden County, MA: when it starts and ends
Mosquito months in Hampden County
In a normal year mosquito season in Hampden County, MA starts around April 21 and ends around October 19, about 26 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Hampden County, and when
- Start tipping out standing water weekly by April 7.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 19.
- 7 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Hampden County against the rest of MA
Hampden County has the 7th longest season of 14 MA counties, at 181 days against 194 in Plymouth County and 163 in Berkshire County. Its mean temperature is 49.5°F.
- Bristol County: April 23 to October 24 (184 days, 8 WNV)
- Barnstable County: April 28 to October 29 (184 days, 7 WNV)
- Dukes County: April 27 to October 25 (181 days, 0 WNV)
- Middlesex County: April 21 to October 18 (180 days, 65 WNV)
West Nile in Hampden County
From 1999 to 2025, CDC ArboNET counted 13 human West Nile cases in Hampden County (13 neuroinvasive) across 9 years. The worst was 2012 with 3; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.