Mosquito season in Oliver County, ND: when it starts and ends
Mosquito months in Oliver County
In a normal year mosquito season in Oliver County, ND starts around May 4 and ends around October 3, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Oliver County, and when
- Start tipping out standing water weekly by April 20.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 3.
- 1 West Nile case since 2016 (last 2017): you should use repellent at dusk July, more so if over 60.
Oliver County against the rest of ND
Oliver County has the 13th longest season of 53 ND counties, at 152 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 42.4°F.
- Sargent County: May 3 to October 4 (153 days, 8 WNV)
- Ransom County: May 4 to October 3 (153 days, 4 WNV)
- Stutsman County: May 4 to October 3 (152 days, 20 WNV)
- Slope County: May 5 to October 5 (152 days, 0 WNV)
West Nile in Oliver County
From 1999 to 2025, CDC ArboNET counted 12 human West Nile cases in Oliver County (1 neuroinvasive) across 4 years. The worst was 2003 with 7; the latest was 2017.
Background: when the season starts across the US; how the dates are worked out.