Mosquito season in Sheridan County, ND: when it starts and ends
Mosquito months in Sheridan County
In a normal year mosquito season in Sheridan County, ND starts around April 30 and ends around October 7, about 23 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sheridan 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 7.
- 2 West Nile cases since 2016 (last 2018): you should use repellent at dusk July to August, more so if over 60.
Sheridan County against the rest of ND
Sheridan County has the 1st longest season of 53 ND counties, at 160 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 43.3°F.
- Richland County: May 1 to October 6 (159 days, 11 WNV)
- Sioux County: May 1 to October 6 (159 days, 4 WNV)
West Nile in Sheridan County
From 1999 to 2025, CDC ArboNET counted 10 human West Nile cases in Sheridan County (1 neuroinvasive) across 5 years. The worst was 2003 with 6; the latest was 2018.
More: how the dates are worked out · when mosquitoes go away for the winter.