Lake Tahoe 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 Lake Tahoe.
The Tahoe basin sits at 6,225 feet, enclosed on all sides by peaks reaching above 10,000 feet. Cold air drains off those slopes onto the lake every night and has nowhere to go, which makes the basin one of the most reliable smoke traps in the Sierra Nevada. Smoke that arrives in the afternoon is usually still there the following morning.
Where the smoke comes from
West-slope Sierra fires are the primary source, since smoke crosses the crest and settles into the basin. Northern California fires further out contribute a broader haze, and fires in the basin itself, though less frequent, produce the most severe conditions because there is no dilution distance at all.
How long it lasts
Slowly, and only with a genuine wind event. The basin's own diurnal breezes circulate air across the lake without exporting much of it. Tahoe smoke episodes routinely run a week or longer, which is why the hourly outlook is more useful for planning a trip than a single current reading.
Past smoke events
The Caldor Fire in August and September 2021 crossed the Sierra crest, forced the evacuation of South Lake Tahoe, and left the basin under hazardous air for weeks. The 2007 Angora Fire burned inside the basin itself, and the 2020 and 2018 seasons both produced extended regional smoke.
Trails and viewpoints
The Tahoe Rim Trail, Desolation Wilderness, and the lake itself are the draw, and all of them are inside the trap. The ridgelines above 9,000 feet on the west side occasionally sit above a shallow layer, but during a real episode the basin fills to well above the surrounding peaks and there is no local escape.
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.