Mosquito season in Carroll County, NH: when it starts and ends
Mosquito months in Carroll County
In a normal year mosquito season in Carroll County, NH starts around May 7 and ends around October 3, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Carroll County, and when
- Start tipping out standing water weekly by April 23.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 3.
- No West Nile cases since 2016, so bites in Carroll County are a nuisance; check window screens.
Carroll County against the rest of NH
Carroll County has the 8th longest season of 10 NH counties, at 150 days against 170 in Strafford County and 141 in Coos County. Its mean temperature is 43.3°F.
- Merrimack County: May 3 to October 9 (159 days, 1 WNV)
- Sullivan County: May 5 to October 7 (156 days, 0 WNV)
- Grafton County: May 8 to October 4 (149 days, 0 WNV)
- Coos County: May 12 to September 30 (141 days, 0 WNV)
West Nile in Carroll County
CDC ArboNET lists no human West Nile cases for Carroll County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 1 of those years.
See how the dates are worked out, and when the season starts across the US.