Mosquito season in Johnson County, MO: when it starts and ends
Mosquito months in Johnson County
In a normal year mosquito season in Johnson 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 Johnson 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 Johnson County are a nuisance; check window screens.
Johnson County against the rest of MO
Johnson County has the 58th longest season of 115 MO counties, at 211 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 54.9°F.
- Platte County: April 2 to October 30 (212 days, 3 WNV)
- Christian County: April 3 to November 1 (212 days, 0 WNV)
- Warren County: April 3 to October 31 (211 days, 0 WNV)
- St. Clair County: April 4 to November 1 (211 days, 0 WNV)
West Nile in Johnson County
From 1999 to 2025, CDC ArboNET counted 2 human West Nile cases in Johnson County (0 neuroinvasive) across 2 years. The worst was 2007 with 1; the latest was 2007.
See how the dates are worked out, and when the season starts across the US.