Mosquito season in Warren County, MO: when it starts and ends
Mosquito months in Warren County
In a normal year mosquito season in Warren County, MO starts around April 3 and ends around October 31, about 30 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Warren County, and when
- Start tipping out standing water weekly by March 20.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 31.
- No West Nile cases since 2016, so bites in Warren County are a nuisance; check window screens.
Warren County against the rest of MO
Warren County has the 59th longest season of 115 MO counties, at 211 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 54.5°F.
- Christian County: April 3 to November 1 (212 days, 0 WNV)
- Johnson County: April 3 to October 31 (211 days, 0 WNV)
- St. Clair County: April 4 to November 1 (211 days, 0 WNV)
- Stone County: April 4 to November 1 (211 days, 2 WNV)
West Nile in Warren County
CDC ArboNET lists no human West Nile cases for Warren County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 4 of those years.
Background: when the season starts across the US; how the dates are worked out.