Mosquito season in Polk County, MO: when it starts and ends
Mosquito months in Polk County
In a normal year mosquito season in Polk County, MO starts around April 1 and ends around November 1, about 31 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Polk County, and when
- Start tipping out standing water weekly by March 18.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after November 1.
- No West Nile cases since 2016, so bites in Polk County are a nuisance; check window screens.
Polk County against the rest of MO
Polk County has the 47th longest season of 115 MO counties, at 214 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 56°F.
- Bollinger County: April 1 to November 1 (214 days, 0 WNV)
- Moniteau County: April 1 to November 1 (214 days, 0 WNV)
- St. Francois County: April 1 to November 1 (214 days, 1 WNV)
- Cooper County: April 1 to November 1 (213 days, 0 WNV)
West Nile in Polk County
CDC ArboNET lists no human West Nile cases for Polk County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 4 of those years.
More: how the dates are worked out · when mosquitoes go away for the winter.