Mosquito season in McCook County, SD: when it starts and ends
Mosquito months in McCook County
In a normal year mosquito season in McCook County, SD starts around April 29 and ends around October 8, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in McCook County, and when
- Start tipping out standing water weekly by April 15.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 8.
- 9 West Nile cases since 2016 (last 2023): you should use repellent at dusk July to July, more so if over 60.
McCook County against the rest of SD
McCook County has the 30th longest season of 66 SD counties, at 162 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 44.9°F.
- Jackson County: May 1 to October 11 (163 days, 1 WNV)
- Todd County: May 1 to October 11 (163 days, 3 WNV)
- Roberts County: April 29 to October 8 (162 days, 5 WNV)
- Kingsbury County: April 29 to October 8 (161 days, 17 WNV)
West Nile in McCook County
From 1999 to 2025, CDC ArboNET counted 25 human West Nile cases in McCook County (6 neuroinvasive) across 13 years. The worst was 2003 with 4; the latest was 2023.
Background: reading the West Nile counts; how the dates are worked out.