Mosquito season in Griggs County, ND: when it starts and ends
Mosquito months in Griggs County
In a normal year mosquito season in Griggs County, ND starts around May 7 and ends around October 1, about 21 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Griggs 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 October 1.
- 6 West Nile cases since 2016 (last 2025): you should use repellent at dusk July, more so if over 60.
Griggs County against the rest of ND
Griggs County has the 32nd longest season of 53 ND counties, at 147 days against 160 in Sheridan County and 135 in Rolette County. Its mean temperature is 39.8°F.
- Foster County: May 6 to October 1 (148 days, 3 WNV)
- McIntosh County: May 7 to October 2 (148 days, 4 WNV)
- Stark County: May 8 to October 2 (147 days, 21 WNV)
- Ramsey County: May 7 to September 30 (146 days, 12 WNV)
West Nile in Griggs County
From 1999 to 2025, CDC ArboNET counted 12 human West Nile cases in Griggs County (4 neuroinvasive) across 8 years. The worst was 2003 with 3; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.