Soupy fog and smog that lingered over the Salt Lake Valley on Sunday caused cancellations of nearly half the flights at the Salt Lake City International Airport.
A storm forecast for Monday, however, should help clear the air.
Flights continued Sunday evening, and airport officials hope to return to full capacity sometime Monday. The airport reported 113 inbound and outbound flights cancelled Sunday, airport spokeswoman Barbara Gann said.
"We're anticipating more flight disruptions in the morning, until the heavy fog is lifted," Gann said. She noted the airport never was technically closed Sunday, but flight traffic was halved.
She recommends travelers monitor flight schedules with airlines.
The National Weather Service issued a dense fog advisory for most of Northern Utah, stretching from the Nevada border through the Wasatch Mountains. Rain is likely Monday morning.
The fog started forming early Sunday as temperatures dropped. It filled the Salt Lake Valley and created wide pockets of fog throughout northern Utah, said Peter Wilensky, lead forecaster for the National Weather Service in Salt Lake City. It spread north through Cache Valley and the Bear River Valley.
"People need to be cautious while driving because seeing a stopped car in front of you will be difficult," Wilensky said. Drivers should use their low beam headlights and watch for black ice. Overpasses and bridges can be slippery, he said.
A Pacific storm should move in Monday, bringing rain and stirring the air enough to clear the fog and most of the smog, Wilensky said. The conditions should dissipate by Monday afternoon, he said.
Tribune reporter Erin Alberty contributed to this report.