Boise broke a 74-year-old temperature record on Thursday. Here’s how cold it got
The temperature in Boise plummeted to 14 degrees Thursday morning — a record low for the city for March 10.
The early-morning freeze marked the coldest March day in the city since 1993 and broke the March 10 record by a single degree — it was 15 on this day in 1948, according to the National Weather Service.
The cold temperatures came from a blast of arctic air from Canada permeating the Treasure Valley, according to Idaho News 6 meteorologist Scott Dorval. A combination of low winds and a clear sky allowed any heat in the area to escape and cold air to take its place.
It’s a phenomenon called the radiation effect, Dorval told the Idaho Statesman. When warmth from the sun hits the ground, it absorbs and keeps heat near the surface, but when nighttime comes, the heat rises. If there is cloud cover, that keeps the heat closer to the surface, but a lack of clouds allows warm air out and cool air underneath.
“If there’s cloud cover, it acts like a blanket and ... it doesn’t allow that radiation cooling effect,” Dorval said.
Other areas of Idaho, such as Mountain Home and Pocatello — which was in the single digits — saw even colder temperatures Thursday. While Boise’s temperatures rebounded back into the mid-30s by the afternoon, Pocatello remained in the low 20s, as the air from the north rushed through the valleys of the Rocky Mountains.
Temperatures will rebound in the Treasure Valley through the weekend, with Saturday’s high forecast at 62. A chance for rain next Tuesday offers a shot at the most precipitation Boise has seen since December, Dorval said.
