Mosquito season in McPherson County, SD: when it starts and ends
Mosquito months in McPherson County
In a normal year mosquito season in McPherson County, SD starts around May 4 and ends around October 3, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in McPherson County, and when
- Start tipping out standing water weekly by April 20.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 3.
- 4 West Nile cases since 2016 (last 2019): you should use repellent at dusk July, more so if over 60.
McPherson County against the rest of SD
McPherson County has the 61st longest season of 66 SD counties, at 152 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 41.9°F.
- Lyman County: May 3 to October 5 (155 days, 4 WNV)
- Fall River County: May 5 to October 7 (155 days, 1 WNV)
- Harding County: May 5 to October 5 (152 days, 0 WNV)
- Meade County: May 6 to October 3 (150 days, 7 WNV)
West Nile in McPherson County
From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in McPherson County (4 neuroinvasive) across 10 years. The worst was 2003 with 5; the latest was 2019.
See how the dates are worked out, and reading the West Nile counts.