Mosquito season in Stanley County, SD: when it starts and ends
Mosquito months in Stanley County
In a normal year mosquito season in Stanley County, SD starts around May 1 and ends around October 5, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Stanley County, and when
- Start tipping out standing water weekly by April 17.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 5.
- 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Stanley County against the rest of SD
Stanley County has the 52nd longest season of 66 SD counties, at 157 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 47°F.
- Campbell County: May 1 to October 6 (158 days, 3 WNV)
- Faulk County: May 1 to October 6 (158 days, 14 WNV)
- Clark County: May 2 to October 6 (157 days, 11 WNV)
- Codington County: May 2 to October 6 (157 days, 25 WNV)
West Nile in Stanley County
From 1999 to 2025, CDC ArboNET counted 18 human West Nile cases in Stanley County (4 neuroinvasive) across 7 years. The worst was 2003 with 9; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.