Mosquito season in Lincoln County, SD: when it starts and ends

Mosquito months in Lincoln County

In a normal year mosquito season in Lincoln County, SD starts around April 24 and ends around October 11, about 24 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Lincoln County, and when

• Start tipping out standing water weekly by April 10.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 11.
• 39 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to July, and check SD spray notices.

Lincoln County against the rest of SD

Lincoln County has the 13th longest season of 66 SD counties, at 170 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 45.9°F.

• Brule County: April 25 to October 14 (171 days, 4 WNV)
• Clay County: April 24 to October 11 (170 days, 8 WNV)
• Gregory County: April 26 to October 13 (170 days, 3 WNV)
• Jones County: April 27 to October 13 (168 days, 0 WNV)

West Nile in Lincoln County

From 1999 to 2025, CDC ArboNET counted 79 human West Nile cases in Lincoln County (29 neuroinvasive) across 17 years. The worst was 2018 with 11; the latest was 2025.

See how the dates are worked out, and reading the West Nile counts.