Mosquito season in Cache County, UT: when it starts and ends
Mosquito months in Cache County
In a normal year mosquito season in Cache County, UT starts around April 27 and ends around October 12, about 24 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Cache County, and when
- Start tipping out standing water weekly by April 13.
- Book any yard treatment for late April, ahead of the July peak.
- Repellent can go away after October 12.
- 22 West Nile cases since 2016: you should wear EPA-registered repellent at dusk July to August, and check UT spray notices.
Cache County against the rest of UT
Cache County has the 11th longest season of 29 UT counties, at 168 days against 210 in Salt Lake County and 82 in Summit County. Its mean temperature is 47.8°F.
- San Juan County: April 24 to October 17 (176 days, 2 WNV)
- Carbon County: April 24 to October 15 (174 days, 0 WNV)
- Tooele County: April 28 to October 12 (167 days, 0 WNV)
- Beaver County: April 30 to October 14 (167 days, 0 WNV)
West Nile in Cache County
From 1999 to 2025, CDC ArboNET counted 38 human West Nile cases in Cache County (20 neuroinvasive) across 8 years. The worst was 2025 with 15; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.