Mosquito season in Traill County, ND: when it starts and ends
Mosquito months in Traill County
In a normal year mosquito season in Traill County, ND starts around May 2 and ends around October 5, about 22 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Traill County, and when
- Start tipping out standing water weekly by April 18.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after October 5.
- 5 West Nile cases since 2016 (last 2019): you should use repellent at dusk July to July, more so if over 60.
Traill County against the rest of ND
Traill County has the 5th longest season of 53 ND counties, at 157 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 41.9°F.
- Sioux County: May 1 to October 6 (159 days, 4 WNV)
- Dickey County: April 30 to October 5 (158 days, 9 WNV)
- LaMoure County: May 2 to October 5 (156 days, 6 WNV)
- Walsh County: May 2 to October 4 (154 days, 5 WNV)
West Nile in Traill County
From 1999 to 2025, CDC ArboNET counted 18 human West Nile cases in Traill County (2 neuroinvasive) across 9 years. The worst was 2007 with 6; the latest was 2019.
Background: reading the West Nile counts; how the dates are worked out.