Mosquito season in Brookings County, SD: when it starts and ends
Mosquito months in Brookings County
In a normal year mosquito season in Brookings County, SD starts around May 1 and ends around October 6, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Brookings 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 6.
- 27 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to July, and check SD spray notices.
Brookings County against the rest of SD
Brookings County has the 49th longest season of 66 SD counties, at 158 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 43.3°F.
- Walworth County: May 1 to October 7 (159 days, 17 WNV)
- Butte County: May 2 to October 8 (159 days, 3 WNV)
- Campbell County: May 1 to October 6 (158 days, 3 WNV)
- Faulk County: May 1 to October 6 (158 days, 14 WNV)
West Nile in Brookings County
From 1999 to 2025, CDC ArboNET counted 77 human West Nile cases in Brookings County (25 neuroinvasive) across 14 years. The worst was 2003 with 19; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.