Idaho – Clear skies stretch over the Treasure Valley this morning, but the calm comes with a cost. Cold air sits heavy in low spots, and a dull haze lingers near the ground. The stillness traps pollutants close to the surface, setting the stage for unhealthy air as New Year’s celebrations approach.
According to the National Weather Service in Boise, an Air Stagnation Advisory remains in effect through early Saturday morning. Light winds and a strong temperature inversion are limiting vertical mixing, allowing pollutants to build across the lower Treasure Valley, including Boise, Nampa, Caldwell, and surrounding communities.
Temperatures start the day in the upper 20s and climb into the low 40s this afternoon under sunny skies. While the weather feels quiet, the lack of wind prevents air quality from improving. People with asthma, heart disease, or other respiratory conditions may notice symptoms worsening, especially during outdoor activity.
In Boise, conditions stay mostly dry into New Year’s Day 2026, though clouds increase and rain chances rise later in the day. That incoming moisture may eventually help scour out the stagnant air, but not before several more cold, hazy mornings. Overnight lows near freezing allow inversions to strengthen again each night.
Residents are urged to limit activities that add pollution, including wood burning, when possible. Avoid prolonged outdoor exercise during the worst air quality periods. Keep windows closed during colder mornings to reduce indoor exposure.
Drivers won’t face major weather hazards, but visibility can appear muted under the haze, especially during sunrise and sunset. Roads remain dry overall, though cold mornings may still create frost in shaded areas.
Rain chances increase later this week and into the first weekend of 2026, which could finally help clear the air. Until then, winter’s quiet grip keeps pollution locked in place. Noticing haze or breathing issues this morning? Share what conditions feel like where you live.
Five-Day Outlook for Boise, Idaho
Today: Sunny, high near 42
Wednesday: Partly sunny, high near 43
New Year’s Day 2026 (Thursday): Chance of rain, high near 44
Friday: Chance of rain, high near 53
Saturday: Chance of rain, high near 52
