Mosquito season in Salt Lake County, UT: when it starts and ends
Mosquito months in Salt Lake County
In a normal year mosquito season in Salt Lake County, UT starts around April 2 and ends around October 29, about 30 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Salt Lake County, and when
- Start tipping out standing water weekly by March 19.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 29.
- 70 West Nile cases since 2016: you should wear EPA-registered repellent at dusk June to August, and check UT spray notices.
Salt Lake County against the rest of UT
Salt Lake County has the 1st longest season of 29 UT counties, at 210 days against 210 in Salt Lake County and 82 in Summit County. Its mean temperature is 55.3°F.
- Wayne County: April 5 to October 24 (202 days, 0 WNV)
- Grand County: April 8 to October 26 (201 days, 4 WNV)
West Nile in Salt Lake County
From 1999 to 2025, CDC ArboNET counted 185 human West Nile cases in Salt Lake County (100 neuroinvasive) across 18 years. The worst was 2006 with 57; the latest was 2025.
Background: reading the West Nile counts; how the dates are worked out.