Mosquito season in Todd County, SD: when it starts and ends
Mosquito months in Todd County
In a normal year mosquito season in Todd County, SD starts around May 1 and ends around October 11, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Todd 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 11.
- 3 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Todd County against the rest of SD
Todd County has the 29th longest season of 66 SD counties, at 163 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 46.9°F.
- Mellette County: April 30 to October 10 (163 days, 4 WNV)
- Jackson County: May 1 to October 11 (163 days, 1 WNV)
- McCook County: April 29 to October 8 (162 days, 9 WNV)
- Roberts County: April 29 to October 8 (162 days, 5 WNV)
West Nile in Todd County
From 1999 to 2025, CDC ArboNET counted 24 human West Nile cases in Todd County (10 neuroinvasive) across 9 years. The worst was 2003 with 12; the latest was 2025.
More: how the dates are worked out · when mosquitoes go away for the winter.