Salt Lake City 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 Salt Lake City.
Salt Lake City sits at about 4,300 feet in a closed bowl: the Wasatch Range rises to 11,000 feet on the east, the Oquirrhs wall off the west, and the Great Salt Lake sits at the north end. The valley's winter inversions are nationally known, and summer smoke exploits the same geometry with a shallower version that forms overnight and burns off later each morning.
Where the smoke comes from
Utah's own fires matter, but most bad-air days here are imported. California, Nevada, Idaho, and Oregon smoke arrives on westerly and northwesterly flow, crosses the Great Basin, and drops into the valley. Because the source is usually hundreds of miles away, the smoke arrives as a broad regional layer rather than a discrete plume.
How long it lasts
The bowl needs a real wind event to flush. Lake-driven breezes shuffle air within the valley without removing much of it, so a smoke layer can persist through several days of otherwise pleasant weather. Afternoon mixing gives the daily minimum concentration, and overnight settling gives the maximum.
Past smoke events
August 2020 and July 2021 both produced readings that put Salt Lake City at or near the worst air quality in the world on individual days. The 2018 and 2021 seasons each delivered multiple week-long episodes.
Running, riding, and trailheads
Big and Little Cottonwood, Millcreek, and City Creek canyons all climb steeply out of the valley air within a few miles of the trailhead. On a trapped morning the canyon mouths and the canyon tops can differ by an entire AQI category, which is the single most useful local fact for planning a run or a ride.
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.