Air Quality in Missoula, Montana — Live
Live readings from PurpleAir sensors across Missoula — with free alerts when winter inversions or wildfire smoke roll into the valley.
AQI 9 from 5 PurpleAir sensors · Trending up · data from PurpleAir
As of , the air quality in Missoula, Montana is AQI 9 — Good and rising — with PM2.5 at 1.6 µg/m³, the median of 5 live PurpleAir sensors reading 0 to 52. 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 Missoula: 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 Missoula and Lolo, Frenchtown, Bonner, East Missoula. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Missoula
The sensors Canairy reads in Missoula are 52 AQI points apart right now, from Good to Moderate, which is the whole reason one city-wide number can mislead you: the median describes air you may not be standing in.
| From city center | AQI | Category |
|---|---|---|
| 0.4 mi NNE | 8 | Good |
| 2.2 mi S | 11 | Good |
| 2.4 mi ESE | 0 | Good |
| 3.4 mi ENE | 9 | Good |
| 4.8 mi NW | 52 | Moderate |
Missoula sits at the hub of five valleys, where the Bitterroot, Sapphire, Garnet, and Rattlesnake ranges converge around three rivers, and most of the year the air here is genuinely clean. The trouble shows up at both ends of the calendar: cold, still nights from November through February trap wood smoke against the valley floor, and dry summers can bring wildfire smoke down from the surrounding forests. The same mountain ring that makes Missoula beautiful is what holds bad air in place once the wind stops.
What Canairy does for Missoula
A clear verdict
Not just a number — a plain-English call for Missoula: 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 Missoula or across the country, on one screen.
Why Missoula's winters trap wood smoke
Missoula sits in a bowl at the convergence of the Bitterroot, Sapphire, Garnet, and Rattlesnake ranges - locals call it the hub of five valleys. On cold, calm nights that ring of mountains holds a temperature inversion in place over the valley floor, and instead of rising and dispersing, smoke from chimneys sinks and pools right where people are breathing it. The city and county recognized the problem early: Missoula's Air Stagnation Zone was designated in 1981, and it still extends roughly four miles beyond the city limits today.
In 1994, the county banned installing new wood stoves inside that zone altogether - only EPA-certified pellet stoves and gas appliances are allowed for new installations, and an existing non-compliant stove has to be removed when a property is sold. A 2006-2007 study of Missoula's winter air found residential wood burning responsible for 55 percent of wintertime PM2.5, with ammonium nitrate (18 percent) and industry (19 percent) making up most of the rest. The county also requires oxygenated fuel blends for vehicles every November through February - the valley's winter pollution problem was never just one source.
Stage I and Stage II air alerts
When wood smoke starts to build up inside the Air Stagnation Zone, Missoula City-County Health steps in with a two-tier alert system. A Stage I alert bars any visible smoke from a fireplace, wood stove, or other solid-fuel device within the zone unless the owner holds a specific permit. If conditions worsen, a Stage II alert extends the restrictions across the larger Impact Zone M, a wider ring around the valley.
These aren't hypothetical rules - they get called on real winter days when the inversion locks in and the valley's monitors start climbing. If you heat with wood, or you're just trying to decide whether to keep the windows shut, knowing which stage is in effect matters more here than in most towns, because the same still air that traps smoke also means one side of the valley can be noticeably worse than another at the same hour.
Wildfire smoke has its own bad years
Missoula's other air problem comes from farther away. The county's own health department points to 2000, 2003, 2007, 2012, and 2015 as its worst wildfire-smoke years, when fires burning across western Montana and the wider Northern Rockies filled the valley with smoke for days at a stretch. In a severe fire season, that summer smoke - not winter wood burning - becomes Missoula County's single biggest source of PM2.5 pollution for the year.
Unlike the wood-smoke season, wildfire smoke doesn't need a local inversion to make itself felt - a large fire burning in Idaho or western Montana can fill the valley with haze even when the sky over Missoula itself is empty of flame. Because it's driven by whatever happens to be burning that particular summer, the timing and severity vary a lot from one year to the next, which is exactly why Canairy tracks the sensors continuously instead of asking you to remember which years were bad.
Missoula air quality FAQ
What is the air quality in Missoula right now?
As of September 14, 2026 at 3:33 PM MDT, the air quality in Missoula, Montana is AQI 9 — Good — with PM2.5 at 1.6 µg/m³, the median of 5 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Why does Missoula get smoky in winter?
Missoula sits in a bowl surrounded by the Bitterroot, Sapphire, Garnet, and Rattlesnake ranges, and on cold, calm nights that geography traps a temperature inversion over the valley floor. Smoke from wood stoves and fireplaces has nowhere to go, which is why the county designated an Air Stagnation Zone in 1981 and banned new wood stove installations inside it in 1994.
Which wildfires have hit Missoula's air quality hardest?
Missoula County's health department points to 2000, 2003, 2007, 2012, and 2015 as the worst wildfire-smoke years, when fires across western Montana and the Northern Rockies filled the valley with smoke for days at a time. In a bad fire season, that summer smoke becomes the county's single largest source of PM2.5 for the year, outweighing even the wintertime wood-smoke problem.
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 Missoula, 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 Missoula
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