Mosquito season in Rockingham County, NH: when it starts and ends

Mosquito months in Rockingham County

In a normal year mosquito season in Rockingham County, NH starts around April 28 and ends around October 14, about 24 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Rockingham 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 14.
• 2 West Nile cases since 2016 (last 2021): you should use repellent at dusk July to July, more so if over 60.

Rockingham County against the rest of NH

Rockingham County has the 2nd longest season of 10 NH counties, at 169 days against 170 in Strafford County and 141 in Coos County. Its mean temperature is 47.4°F.

• Strafford County: April 28 to October 14 (170 days, 0 WNV)
• Belknap County: April 30 to October 13 (166 days, 0 WNV)
• Hillsborough County: April 30 to October 11 (164 days, 0 WNV)

West Nile in Rockingham County

From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Rockingham County (1 neuroinvasive) across 3 years. The worst was 2021 with 1; the latest was 2021.

More: how the dates are worked out · when the season starts across the US.