Mosquito season in Hand County, SD: when it starts and ends
Mosquito months in Hand County
In a normal year mosquito season in Hand County, SD starts around April 29 and ends around October 9, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Hand County, and when
- Start tipping out standing water weekly by April 15.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 9.
- 6 West Nile cases since 2016 (last 2025): you should use repellent at dusk July to August, more so if over 60.
Hand County against the rest of SD
Hand County has the 25th longest season of 66 SD counties, at 163 days against 179 in Yankton County and 139 in Lawrence County. Its mean temperature is 45.2°F.
- Beadle County: April 27 to October 8 (164 days, 32 WNV)
- Buffalo County: April 28 to October 9 (164 days, 2 WNV)
- Ziebach County: April 29 to October 9 (163 days, 2 WNV)
- Mellette County: April 30 to October 10 (163 days, 4 WNV)
West Nile in Hand County
From 1999 to 2025, CDC ArboNET counted 23 human West Nile cases in Hand County (8 neuroinvasive) across 10 years. The worst was 2003 with 8; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.