For more than a week, Salt Lake City has been pestered by a haze of pollutants that are trapped in cold air at the bottom of the valley. Soon, that’s going to change, according to the National Weather Service.
On Friday and Saturday, an incoming storm system is likely to clean out the valley at last, according to Monica Traphagan, a senior meteorologist at the National Weather Service’s Salt Lake City office.
According to Traphagan, the dense haze that’s settled in the Salt Lake Valley was caused when cold air was trapped by a high-pressure system between the Wasatch Range and the Oquirrh Mountains.
(Trent Nelson | The Salt Lake Tribune) An inversion over Salt Lake City on Thursday, Jan. 15, 2026.
Unable to escape the geographic bowl, the stagnant air continues to accumulate pollution from factories, oil refineries, cars and fireplaces, Traphagan said.
Because of the weather event — called an inversion — Traphagan said Salt Lake City’s air quality reached the worst in the nation last week.
To clear the smog, Salt Lake City needs strong winds or an influx of fresh cold air to sink into the valley and flush out the pollutants.
Last Friday, the haze was partially cleared out by a storm system, according to Traphagan. Cold air and pollutants were still trapped in the valley, but the inversion’s hold was weakened, and air quality improved, Traphagan said.
(Trent Nelson | The Salt Lake Tribune) An inversion over Salt Lake City on Thursday, Jan. 15, 2026.
On Wednesday, Utah’s Department of Environmental Quality reported Salt Lake County’s air quality was moderate. Before the partial flush-out, the air in Salt Lake County had been deemed unhealthy for sensitive groups.
Traphagan said an incoming storm system will likely bring an air mass cold enough to fully flush out the trapped pollutants on Friday or Saturday.
The storm likely won’t bring much precipitation to most of the state, Traphagan added, with a potential exception for some moisture falling over southern Utah.