Mosquito season in Slope County, ND: when it starts and ends
Mosquito months in Slope County
In a normal year mosquito season in Slope County, ND starts around May 5 and ends around October 5, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Slope County, and when
- Start tipping out standing water weekly by April 21.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 5.
- No West Nile cases since 2016, so bites in Slope County are a nuisance; check window screens.
Slope County against the rest of ND
Slope County has the 15th longest season of 53 ND counties, at 152 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 44.1°F.
- Oliver County: May 4 to October 3 (152 days, 1 WNV)
- Stutsman County: May 4 to October 3 (152 days, 20 WNV)
- McHenry County: May 4 to October 2 (151 days, 14 WNV)
- Ward County: May 4 to October 2 (151 days, 35 WNV)
West Nile in Slope County
From 1999 to 2025, CDC ArboNET counted 3 human West Nile cases in Slope County (0 neuroinvasive) across 2 years. The worst was 2003 with 2; the latest was 2007.
More: how the dates are worked out · when the season starts across the US.