Mosquito season in Clark County, MO: when it starts and ends
Mosquito months in Clark County
In a normal year mosquito season in Clark County, MO starts around April 11 and ends around October 24, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Clark County, and when
- Start tipping out standing water weekly by March 28.
- Book any yard treatment for mid April, ahead of the July peak.
- Repellent can go away after October 24.
- No West Nile cases since 2016, so bites in Clark County are a nuisance; check window screens.
Clark County against the rest of MO
Clark County has the 102nd longest season of 115 MO counties, at 196 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 51.6°F.
- Daviess County: April 10 to October 24 (197 days, 0 WNV)
- Harrison County: April 10 to October 25 (197 days, 1 WNV)
- DeKalb County: April 11 to October 24 (196 days, 0 WNV)
- Nodaway County: April 11 to October 23 (195 days, 0 WNV)
West Nile in Clark County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Clark County (1 neuroinvasive) across 1 year. The worst was 2004 with 1; the latest was 2004.
See how the dates are worked out, and when the season starts across the US.