Air quality in Salt Lake County was upgraded from the red zone to orange Thursday morning — meaning that the air is unhealthy for sensitive groups, rather than everybody — thanks to a weak cold front that cleared out much of the fog in valleys along the Wasatch Front.

The National Weather Service is predicting a stronger cold front beginning Friday night that will bring a quick breath of fresh air to valleys as the weekend begins.

It will push pollution out, the NWS says, and bring a chance of snow with light accumulations in northern Utah. However, pressure in the valley will build in time for the beginning of the new week and another inversion will settle in.

Air quality was also in the orange zone Thursday for Davis, Box Elder and Tooele counties, according to the state Division of Air Quality. Utah, Weber and Cache counties had moderate air in the yellow zone Thursday, but all were expected to downgrade to the orange zone Friday. Duchesne and Uintah counties also had moderate air with steady conditions through Friday, while air in Washington and Carbon counties was expected to be good in the green zone.

Temperatures will reach the lower 30s Thursday in the Salt Lake and Tooele valleys, with partly sunny skies and hazy conditions. Clouds will move in during the evening, and haze will continue through the night, with patchy fog after midnight. Lows will drop into the mid-20s before Friday.

Temperatures will be similar Friday with partly cloudy skies, patchy fog in the morning and haze through the day. Saturday will be mostly cloudy with highs in the upper 30s and a 50 percent chance of snow.

For southern Utah residents near St. George, highs will reach about 60 degrees Thursday with sunny skies and high winds blowing northeast at 25 to 35 mph with gusts reaching 60 mph near canyons. Skies will remain clear overnight and throughout the day Friday, with temperatures climbing from lows in the upper 20s Thursday night to about 60 degrees again Friday.

On Friday night, lows will hover at about 30 degrees. Saturday will bring sunny skies in the morning, but clouds will move in as the day wears on. Highs will reach the upper 50s, the NWS says.

The NWS issued a hazardous weather outlook for the entire state Thursday, warning of strong, gusty canyon winds moving north in Washington County in the morning and the possibility of patchy fog that may become dense across Cache Valley, Bear Lake, the Great Salt Lake and Utah Lake.

The Utah Avalanche Center said that the risk was low for avalanches Thursday near Logan, Ogden, Salt Lake, Provo and the Uintas.

For more detailed weather information, visit The Salt Lake Tribune’s weather page at