Boise, ID – The Treasure Valley wakes under crisp, still skies this morning — the kind that look harmless but quietly trap what’s below. With little wind and clear weather expected through the weekend, air quality across southwest Idaho is poised to worsen as a stagnant air pattern locks in through early Monday.
The National Weather Service in Boise has issued an Air Stagnation Advisory for much of southwest Idaho and parts of southeast Oregon. The advisory is in effect from Friday at 5 a.m. through Monday at 5 a.m., warning of extended periods of calm air and limited vertical mixing. This atmospheric setup allows pollutants — from car exhaust to fireplace smoke — to accumulate near the surface.
Health officials caution that people with asthma, COPD, or heart conditions should limit time outdoors, especially during afternoon hours when haze thickens. Residents are also encouraged to reduce wood burning and vehicle trips to help improve air quality. Visibility may become hazy across the valley by Saturday, particularly around Boise, Nampa, and Caldwell.
Temperatures will remain mild, with daytime highs in the mid- to upper-50s through Sunday before cooler, unsettled weather develops early next week. The pattern could shift Monday night into Tuesday, bringing a chance of rain and snow — and much-needed wind to help clear the stagnant air.
Five-Day Outlook (Boise, ID)
- Friday: Sunny, high 57°F, low 34°F.
- Saturday: Sunny, high 55°F, low 33°F.
- Sunday: Mostly sunny, high 52°F, low 35°F.
- Monday: 40% chance of rain, high 55°F, low 42°F.
- Tuesday: 50% chance of rain and snow, high 53°F.
