Mosquito season in Utah County, UT: when it starts and ends
Mosquito months in Utah County
In a normal year mosquito season in Utah County, UT starts around April 9 and ends around October 25, about 28 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Utah County, and when
- Start tipping out standing water weekly by March 26.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 25.
- 28 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check UT spray notices.
Utah County against the rest of UT
Utah County has the 4th longest season of 29 UT counties, at 199 days against 210 in Salt Lake County and 82 in Summit County. Its mean temperature is 53.4°F.
- Wayne County: April 5 to October 24 (202 days, 0 WNV)
- Grand County: April 8 to October 26 (201 days, 4 WNV)
- Davis County: April 16 to October 20 (188 days, 36 WNV)
- Garfield County: April 22 to October 20 (181 days, 0 WNV)
West Nile in Utah County
From 1999 to 2025, CDC ArboNET counted 113 human West Nile cases in Utah County (55 neuroinvasive) across 11 years. The worst was 2006 with 65; the latest was 2025.
More: how the dates are worked out · reading the West Nile counts.