Heavy fog settled into the Treasure Valley overnight, affecting travel both on the ground and in the air. Many flights in and out of the Boise Airport have been delayed or canceled.

The National Weather Service sent out a dense-fog advisory for the valley starting at 10 p.m. Thursday and continuing until 10 a.m. Friday. The fog started to lift just after noon, but the damage had already been done at the Boise Airport.

There were 50 flights delayed in and out of Boise on Friday, and 13 were canceled in the early morning. And it wasn’t just the fog affecting air travel, Boise Airport spokesperson Jennifer Kronberg told the Idaho Statesman in an email.

At the same time dense fog was affecting visibility, there was an outage involving Federal Aviation Administration navigational aids, Kronberg said.

Each airline also has its own regulations for operating in low-visibility conditions, she told the Statesman.

Kronberg said operations were resuming normally by the early afternoon.

“We appreciate the patience of our passengers and encourage travelers to check directly with their airline for the latest flight status updates,” she said in the email.

Foggy conditions also affect road travel, Boise National Weather Service meteorologist Les Colin told the Statesman. He recommended driving slower, keeping a distance from other cars and using low-beam lights.

“Patches of dense fog can be a real hazard on the roads,” he said.

The fog will return Saturday morning, Colin said, and is likely to stick around until Sunday.

This story was originally publishedNovember 21, 2025 at 12:50 PM.

Shannon Tyler

Idaho Statesman

970-815-1582