Mosquito season in Marion County, MO: when it starts and ends
Mosquito months in Marion County
In a normal year mosquito season in Marion County, MO starts around April 6 and ends around October 28, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Marion County, and when
- Start tipping out standing water weekly by March 23.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 28.
- 1 West Nile case since 2016 (last 2023): you should use repellent at dusk June to August, more so if over 60.
Marion County against the rest of MO
Marion County has the 81st longest season of 115 MO counties, at 205 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 53.2°F.
- Pike County: April 5 to October 29 (207 days, 0 WNV)
- Lincoln County: April 6 to October 29 (206 days, 2 WNV)
- Shannon County: April 6 to October 28 (205 days, 1 WNV)
- Ralls County: April 7 to October 28 (204 days, 0 WNV)
West Nile in Marion County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Marion County (1 neuroinvasive) across 1 year. The worst was 2023 with 1; the latest was 2023.
More: how the dates are worked out · when mosquitoes go away for the winter.