Denver 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 Denver.
Denver sits at 5,280 feet on the South Platte valley floor at the foot of the Front Range. The mountains to the west are high enough to steer weather but the city itself is on open plains, so Denver does not trap smoke the way a mountain valley does. Its problem is arrival from above rather than pooling from below.
Where the smoke comes from
Two distinct kinds, and they behave differently. Local fires in the Front Range foothills and mountain parks produce sharp, terrain-driven smoke. Far more often, smoke from Pacific Northwest and California fires crosses the Divide at altitude, sits as a visible layer aloft in the morning, then mixes down to the surface in the afternoon as the boundary layer deepens over the heated plains.
How long it lasts
The afternoon mixing that clears most cities can make Denver worse, because it connects the surface to a smoke layer that was overhead all morning. Readings frequently peak in mid-afternoon rather than at dawn, which is the opposite of the valley cities. Clearing normally waits for the upper-level flow to change.
Past smoke events
August 2020 briefly gave Denver the worst air quality of any major city in the world, from a combination of the Cameron Peak Fire and West Coast smoke aloft. The East Troublesome Fire in October of the same season added a second, sharper episode.
Running, riding, and trailheads
Front Range trails gain elevation quickly, which cuts both ways: a trailhead at 8,000 feet can be inside the aloft layer while Denver is still clean at street level in the morning. The near-surface product on the map is the one that matches what you breathe on the trail, not the column reading that only tints the skyline.
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.