Mosquito season in Pierce County, ND: when it starts and ends
Mosquito months in Pierce County
In a normal year mosquito season in Pierce County, ND starts around May 7 and ends around September 29, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Pierce County, and when
- Start tipping out standing water weekly by April 23.
- Book any yard treatment for early May, ahead of the July peak.
- Repellent can go away after September 29.
- 4 West Nile cases since 2016 (last 2024): you should use repellent at dusk July, more so if over 60.
Pierce County against the rest of ND
Pierce County has the 37th longest season of 53 ND counties, at 145 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 39°F.
- Steele County: May 7 to September 30 (146 days, 2 WNV)
- Nelson County: May 7 to September 30 (145 days, 1 WNV)
- Benson County: May 8 to September 30 (145 days, 4 WNV)
- Morton County: May 8 to September 30 (145 days, 42 WNV)
West Nile in Pierce County
From 1999 to 2025, CDC ArboNET counted 11 human West Nile cases in Pierce County (4 neuroinvasive) across 5 years. The worst was 2007 with 5; the latest was 2024.
More: how the dates are worked out · reading the West Nile counts.