Monday’s unseasonably cool temperatures will turn positively cold Monday night, with a hard freeze expected in parts of Utah, according to the National Weather Service.
The cold air mass moving across the state dropped temperatures 10 to 15 degrees below normal Monday with an expected high of just 63. The hard freeze is expected between midnight Monday and 9 a.m. Tuesday across the Bear River Valley, the Wasatch Back, Sanpete Valley and Sevier River Valleys.
There’s also the possibility of hard freezes in Cache Valley and parts of Iron County. Temperatures of 28 and below are expected, and the cities of Huntsville, Park City, Heber City, Woodruff, Randolph, Garden City, Manti, Ephraim, Mount Pleasant, Panguitch, Circleville, and Koosharem could all be affected.
The frost could kill crops and other sensitive plants and stands to damage unprotected outdoor plumbing.
It’s an early taste of autumn — the first day of fall is Wednesday — and it’s only temporary. Temperatures are expected to rise as the week continues.
The normal, Sept. 20 high in Salt Lake City is 79 degrees, gradually decreasing to 76 over the next week. The current forecast calls for highs in the low 70s on Tuesday, in the upper 70s on Wednesday and in the low to mid-80s Thursday-Sunday.
The St. George area will get a one-day break from the heat, with a high near 86 on Monday. Then it’s back to the low to mid-90s from Tuesday through Sunday.
There is no precipitation in the forecast.
According to the Utah Department of Environmental Quality, air quality will be green/good through Wednesday in Cache, Carbon, Duchesne, Iron, Tooele, Uintah, Washington and Weber/Box Elder counties.
The forecast calls for green/good on Monday in Salt Lake, Davis and Utah counties, changing to yellow/moderate on Tuesday and Wednesday.