Air Quality in South Lake Tahoe, California — Live
Live readings from PurpleAir sensors around South Lake Tahoe — with free alerts the moment smoke moves in.
AQI 4 from 5 PurpleAir sensors · Trending down · data from PurpleAir
As of , the air quality in South Lake Tahoe, California is AQI 4 — Good and falling — with PM2.5 at 0.8 µg/m³, the median of 5 live PurpleAir sensors reading 0 to 6. Canairy's verdict: Breathe easy.
For scale, that PM2.5 reading is below the World Health Organization's 24-hour guideline of 15 µg/m³. The WHO figure is a daily average and this is a live reading, so read it as a sense of magnitude rather than a formal exceedance — a brief spike and a bad day are not the same thing. More on the WHO guidelines
Pollen today in South Lake Tahoe: weeds pollen is the strongest of the three at a very low level, from Google's pollen forecast. Canairy shows the tree, grass and weed forecast beside the air reading on every plan, including the free one.
Free to download · Live data from PurpleAir & public monitors
Live PurpleAir sensor map for South Lake Tahoe and Stateline, Meyers, Zephyr Cove, Tahoma. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in South Lake Tahoe
The sensors Canairy reads in South Lake Tahoe agree right now — all 5 sit in the Good band, a 6-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 1.5 mi ESE | 4 | Good |
| 3.6 mi ENE | 4 | Good |
| 4.3 mi SW | 0 | Good |
| 5.2 mi NNE | 4 | Good |
| 5.7 mi SW | 6 | Good |
South Lake Tahoe's air is usually some of the cleanest in California, but the city sits in a high mountain basin that traps whatever smoke reaches it. Wildfire seasons have pushed it to hazardous readings, most dramatically in August 2021 when the Caldor Fire forced the entire city to evacuate, and winter brings a quieter haze of wood smoke that settles over the valley on cold, still mornings.
What Canairy does for South Lake Tahoe
A clear verdict
Not just a number — a plain-English call for South Lake Tahoe: open the windows, or keep them shut.
Smoke alerts
A push or text the moment the air crosses your threshold — and again when it clears.
A heads-up before it's bad
Trend alerts catch the air turning, so you can close up the house before the smoke settles in.
Every place you care about
Home, work, the kids' school — across South Lake Tahoe or across the country, on one screen.
The Caldor Fire drove Tahoe's air to the worst readings on record
The Caldor Fire ignited on August 14, 2021, and burned across the Sierra toward the lake for weeks. On August 30, officials ordered the entire city of South Lake Tahoe to evacuate, moving roughly 53,000 people out at once as the fire passed 191,000 acres. For days the basin filled with dense smoke, and air quality across the Tahoe area climbed into the hazardous range, the top of the EPA scale.
Those were the worst readings the region had seen since local monitoring began in 1999. Nearby Tahoe Vista recorded an AQI of 415 at one point, and communities downwind toward Carson City and Virginia City were buried under the same smoke. It was the clearest reminder that a basin ringed by forest can go from pristine to unbreathable in a matter of hours when a fire is close.
The basin traps smoke, in summer and in winter
South Lake Tahoe sits at about 6,225 feet in a fault-formed basin, ringed by peaks that rise to between 9,000 and nearly 11,000 feet. That bowl shape is beautiful, but it holds air in place. When wildfire smoke drifts in during late summer, it can pool over the lake instead of blowing through, which is how the city reached an AQI of 212 during the August 2020 fire season well before Caldor.
Winter brings a different version of the same problem. When snow covers the ground, it chills the air near the surface and a warmer layer settles on top like a lid, an inversion that stops the cold, smoky air from rising and dispersing. Wood stoves, home heating, and idling cars keep feeding particles into that trapped layer, and in 2019 the city's most polluted months for fine particulate were January, October and December. Prescribed burns in the basin add to this too, with smoke hanging low over the valley on still mornings before it lifts.
South Lake Tahoe air quality FAQ
What is the air quality in South Lake Tahoe right now?
As of September 5, 2026 at 5:10 AM PDT, the air quality in South Lake Tahoe, California is AQI 4 — Good — with PM2.5 at 0.8 µg/m³, the median of 5 live PurpleAir sensors. Open the windows. Great for outdoor activity.
How bad did the air get during the Caldor Fire?
During the Caldor Fire in late August 2021, South Lake Tahoe's air quality reached the hazardous range at the very top of the EPA scale, and officials described those days as the worst the region had recorded since monitoring began in 1999. Nearby Tahoe Vista hit an AQI of 415, and on August 30 the entire city was ordered to evacuate as the fire closed in.
Why does South Lake Tahoe get smoky in winter, not just during fire season?
South Lake Tahoe sits in a high mountain basin, and in winter, snow on the ground chills the air near the surface while a warmer layer settles on top like a lid. This is called a temperature inversion, and it traps wood smoke, home-heating exhaust and car emissions in the valley until the weather changes. The city's most polluted months for fine particles are often in winter rather than summer for exactly this reason.
What the AQI numbers mean
| AQI | Category | What it means for you |
|---|---|---|
| 0–50 | Good | Open the windows. Great for outdoor activity. |
| 51–100 | Moderate | Sensitive groups may want to take it slower outside. |
| 101–150 | Unhealthy for Sensitive Groups | Kids, elderly, and respiratory conditions stay closer to home. |
| 151–200 | Unhealthy | Skip outdoor exercise. Close windows. |
| 201–300 | Very Unhealthy | Limit time outside. N95 if you must go. |
| 301+ | Hazardous | Health emergency. Stay inside, run filtration if you have it. |
Canairy lets you tighten these bands if you’re more sensitive than the EPA default, so an alert can fire before the official category changes. How to read the Air Quality Index
Where these readings come from
The AQI at the top of this page is the median of the 5 curated PurpleAir sensors Canairy tracks in and around South Lake Tahoe, with outliers set aside so that one sensor brought indoors — or parked beside a barbecue — cannot set the number for a whole city. Every sensor behind it is listed above with its distance and bearing from the city center. There is no black box here.
In the app, a place you save resolves the same way first. When no neighborhood sensor is reporting it falls back to the nearest EPA AirNow monitor, and anything modeled rather than measured is labelled a regional estimate rather than passed off as a sensor reading. How low-cost sensors compare to regulatory monitors
About Canairy
Canairy is free to download. The free plan covers one saved place with live readings, a plain-English verdict, and push alerts when the air crosses a threshold you choose. Paid plans add more places, faster refreshes, and SMS alerts. It is built by two parents in Sonoma County, California, who got tired of guessing whether it was safe to send the kids outside. Why we built it
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Air quality near South Lake Tahoe
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