Boise wildfire smoke forecast
The map above shows NOAA HRRR-Smoke near-surface PM2.5 for the next 48 hours, updated hourly, with active fires from NIFC and live AQI from EPA AirNow monitors. It opens over Boise.
Boise sits at roughly 2,700 feet in the Treasure Valley, a bowl at the western end of the Snake River Plain with the Boise Foothills rising immediately north and east and the Owyhee Mountains across the valley to the southwest. Cold air drains off the foothills every clear night and settles on the valley floor, taking any smoke in the air down with it.
Where the smoke comes from
Boise is surrounded by fuel of two different kinds. The Boise National Forest and the central Idaho wilderness burn timber to the north and east, while the Owyhee and Great Basin rangelands to the south and west carry fast cheatgrass fires that can put up a large plume in a single afternoon. Oregon's high desert adds a third source on westerly flow.
How long it lasts
The valley is a sink, so clearing depends on wind rather than time. Daytime heating mixes the layer upward and improves readings by afternoon; the following night's drainage flow undoes much of it. Episodes here often show a strong daily rhythm rather than a steady level, and the hourly forecast is more useful than a daily average.
Past smoke events
The 2012 and 2013 seasons, including the Pony and Elk complexes, held the valley in smoke for weeks. August 2015 and the 2021 season repeated it. Boise's worst air of the year is now routinely in August rather than during the winter inversion season.
Running, riding, and trailheads
The Ridge to Rivers network starts at the edge of town and climbs several hundred feet within the first mile, which on inversion mornings can put a rider or runner above the worst of the layer while the Greenbelt along the river sits in it. Bogus Basin, at 6,000 feet, is often clear when downtown is not.
Reading the map
Use the layer toggle to compare NOAA HRRR-Smoke with the ECCC FireWork model. When the two disagree, treat the higher reading as the cautious call.
Near-surface is the product that maps to what you breathe and to AQI, not the high-altitude column that only tints the sunset. A sky that looks bad and a monitor that reads fine are usually both correct, and they are describing different layers of air.