Los Angeles 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 Los Angeles.
The Los Angeles Basin runs from the coast up against the San Gabriel and San Bernardino mountains, and it does not behave like the valley cities to the north. There is no overnight cold-air pool doing the trapping. Instead a daily sea breeze pushes air inland against the mountain wall, so pollution and smoke accumulate at the inland edge of the basin rather than at its centre.
Where the smoke comes from
Los Angeles mostly makes its own smoke. Foothill and canyon fires in the Santa Monicas, the San Gabriels, and the Angeles National Forest sit inside the basin or on its rim, so a fire can go from ignition to citywide smoke in a few hours. Santa Ana winds complicate it: offshore flow drives fire growth while pushing the smoke out to sea, and the air can turn far worse when the gradient relaxes and the sea breeze carries it back inland.
How long it lasts
The sea breeze does not remove smoke from the basin so much as relocate it. Coastal neighbourhoods clear first, and the San Gabriel Valley, Pasadena, and the Inland Empire read worst in the afternoon even when the fire is on the coastal side. Real clearing needs either sustained offshore flow or a trough deep enough to ventilate the whole basin.
Past smoke events
The January 2025 Palisades and Eaton fires burned simultaneously on opposite sides of the basin and produced the most severe urban smoke event in the region's modern record, in a month that was historically outside fire season. The 2020 Bobcat Fire and the 2018 Woolsey Fire both put heavy smoke over large parts of the county.
Running, riding, and trailheads
Griffith Park, the San Gabriel front-range trails, and the Santa Monica Mountains are all inside the basin, and the front-range trailheads sit exactly where the sea breeze piles smoke up against the mountains. Going higher does not reliably help here the way it does in Utah or Colorado, because the accumulation is against the terrain rather than beneath it.
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.