Mosquito season in Grant County, ND: when it starts and ends
Mosquito months in Grant County
In a normal year mosquito season in Grant County, ND starts around May 11 and ends around October 2, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Grant County, and when
- Start tipping out standing water weekly by April 27.
- Book any yard treatment for mid May, ahead of the July peak.
- Repellent can go away after October 2.
- 1 West Nile case since 2016 (last 2018): you should use repellent at dusk July, more so if over 60.
Grant County against the rest of ND
Grant County has the 43rd longest season of 53 ND counties, at 144 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 42.3°F.
- Bowman County: May 9 to October 2 (145 days, 3 WNV)
- Dunn County: May 9 to September 30 (144 days, 3 WNV)
- Renville County: May 9 to September 28 (142 days, 0 WNV)
- Divide County: May 9 to September 27 (141 days, 2 WNV)
West Nile in Grant County
From 1999 to 2025, CDC ArboNET counted 17 human West Nile cases in Grant County (3 neuroinvasive) across 7 years. The worst was 2003 with 7; the latest was 2018.
More: how the dates are worked out · when mosquitoes go away for the winter.