Mosquito season in King William County, VA: when it starts and ends

Mosquito months in King William County

In a normal year mosquito season in King William County, VA starts around March 27 and ends around November 11, about 33 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 King William County, and when

• Start tipping out standing water weekly by March 13.
• Book any yard treatment for late March, ahead of the July peak.
• Repellent can go away after November 11.
• No West Nile cases since 2016, so bites in King William County are a nuisance; check window screens.

King William County against the rest of VA

King William County has the 37th longest season of 133 VA counties, at 229 days against 257 in Norfolk city and 172 in Highland County. Its mean temperature is 59.1°F.

• Alexandria city: March 26 to November 10 (229 days, 8 WNV)
• King and Queen County: March 27 to November 11 (229 days, 0 WNV)
• New Kent County: March 27 to November 11 (229 days, 0 WNV)
• Salem city: March 24 to November 7 (228 days, 0 WNV)

West Nile in King William County

CDC ArboNET lists no human West Nile cases for King William County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 3 of those years.

More: how the dates are worked out · when mosquitoes go away for the winter.