Mosquito season in Sevier County, UT: when it starts and ends
Mosquito months in Sevier County
In a normal year mosquito season in Sevier County, UT starts around May 26 and ends around September 29, about 18 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sevier County, and when
- Start tipping out standing water weekly by May 12.
- Book any yard treatment for late May, ahead of the July peak.
- Repellent can go away after September 29.
- 1 West Nile case since 2016 (last 2019): you should use repellent at dusk July, more so if over 60.
Sevier County against the rest of UT
Sevier County has the 25th longest season of 29 UT counties, at 126 days against 210 in Salt Lake County and 82 in Summit County. Its mean temperature is 44.4°F.
- Duchesne County: May 17 to October 1 (137 days, 8 WNV)
- Iron County: May 17 to September 29 (135 days, 0 WNV)
- Piute County: May 31 to September 23 (115 days, 0 WNV)
- Rich County: May 30 to September 11 (104 days, 0 WNV)
West Nile in Sevier County
From 1999 to 2025, CDC ArboNET counted 1 human West Nile case in Sevier County (1 neuroinvasive) across 1 year. The worst was 2019 with 1; the latest was 2019.
Background: when the season starts across the US; how the dates are worked out.