Mosquito season in Buchanan County, MO: when it starts and ends
Mosquito months in Buchanan County
In a normal year mosquito season in Buchanan County, MO starts around April 9 and ends around October 26, about 29 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Buchanan County, and when
- Start tipping out standing water weekly by March 26.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 26.
- 7 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Buchanan County against the rest of MO
Buchanan County has the 91st longest season of 115 MO counties, at 200 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 53.4°F.
- Ray County: April 8 to October 26 (201 days, 0 WNV)
- Holt County: April 8 to October 25 (200 days, 0 WNV)
- Grundy County: April 9 to October 26 (200 days, 1 WNV)
- Monroe County: April 11 to October 28 (200 days, 0 WNV)
West Nile in Buchanan County
From 1999 to 2025, CDC ArboNET counted 13 human West Nile cases in Buchanan County (8 neuroinvasive) across 8 years. The worst was 2025 with 2; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.