Mosquito season in Lewis County, MO: when it starts and ends
Mosquito months in Lewis County
In a normal year mosquito season in Lewis County, MO starts around April 8 and ends around October 27, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Lewis County, and when
- Start tipping out standing water weekly by March 25.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 27.
- No West Nile cases since 2016, so bites in Lewis County are a nuisance; check window screens.
Lewis County against the rest of MO
Lewis County has the 85th longest season of 115 MO counties, at 202 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 52.5°F.
- Ralls County: April 7 to October 28 (204 days, 0 WNV)
- Clay County: April 8 to October 27 (202 days, 4 WNV)
- Linn County: April 7 to October 25 (201 days, 0 WNV)
- Andrew County: April 8 to October 26 (201 days, 0 WNV)
West Nile in Lewis County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Lewis County (1 neuroinvasive) across 1 year. The worst was 2012 with 1; the latest was 2012.
Background: when mosquitoes go away for the winter; how the dates are worked out.