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

Mosquito months in Oglala Lakota County

In a normal year mosquito season in Oglala Lakota County, SD starts around April 30 and ends around October 12, 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 Oglala Lakota County, and when

• Start tipping out standing water weekly by April 16.
• Book any yard treatment for late April, ahead of the July peak.
• Repellent can go away after October 12.
• 9 West Nile cases since 2016 (last 2023): you should use repellent at dusk July to August, more so if over 60.

Oglala Lakota County against the rest of SD

Oglala Lakota County has the 22nd longest season of 66 SD counties, at 165 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 48°F.

• Jerauld County: April 29 to October 10 (165 days, 5 WNV)
• Sully County: April 29 to October 11 (165 days, 3 WNV)
• Beadle County: April 27 to October 8 (164 days, 32 WNV)
• Buffalo County: April 28 to October 9 (164 days, 2 WNV)

West Nile in Oglala Lakota County

From 1999 to 2025, CDC ArboNET counted 44 human West Nile cases in Oglala Lakota County (19 neuroinvasive) across 10 years. The worst was 2003 with 27; the latest was 2023.

Background: reading the West Nile counts; how the dates are worked out.