Mosquito season in Custer County, SD: when it starts and ends
Mosquito months in Custer County
In a normal year mosquito season in Custer County, SD starts around May 11 and ends around October 4, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Custer County, and when
- Start tipping out standing water weekly by April 27.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 4.
- No West Nile cases since 2016, so bites in Custer County are a nuisance; check window screens.
Custer County against the rest of SD
Custer County has the 65th longest season of 66 SD counties, at 146 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 44.9°F.
- Meade County: May 6 to October 3 (150 days, 7 WNV)
- Hughes County: May 8 to October 2 (147 days, 24 WNV)
- Lawrence County: May 15 to October 1 (139 days, 7 WNV)
West Nile in Custer County
From 1999 to 2025, CDC ArboNET counted 7 human West Nile cases in Custer County (1 neuroinvasive) across 4 years. The worst was 2003 with 4; the latest was 2012.
Background: when the season starts across the US; how the dates are worked out.