Mosquito season in Charles Mix County, SD: when it starts and ends
Mosquito months in Charles Mix County
In a normal year mosquito season in Charles Mix County, SD starts around April 22 and ends around October 17, about 25 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Charles Mix County, and when
- Start tipping out standing water weekly by April 8.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 17.
- 18 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check SD spray notices.
Charles Mix County against the rest of SD
Charles Mix County has the 4th longest season of 66 SD counties, at 178 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 48.7°F.
- Tripp County: April 22 to October 18 (179 days, 4 WNV)
- Douglas County: April 21 to October 16 (178 days, 11 WNV)
- Union County: April 22 to October 15 (176 days, 13 WNV)
- Hutchinson County: April 22 to October 13 (174 days, 18 WNV)
West Nile in Charles Mix County
From 1999 to 2025, CDC ArboNET counted 68 human West Nile cases in Charles Mix County (13 neuroinvasive) across 17 years. The worst was 2003 with 27; the latest was 2025.
Background: reading the West Nile counts; how the dates are worked out.