Air Quality in Duluth, Minnesota — Live
Live readings from PurpleAir sensors across Duluth — with free alerts the moment smoke drifts in.
AQI 21 from 4 PurpleAir sensors · Trending down · data from PurpleAir
As of , the air quality in Duluth, Minnesota is AQI 21 — Good and falling — with PM2.5 at 3.8 µg/m³, the median of 4 live PurpleAir sensors reading 17 to 53. 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 Duluth: grass pollen is the strongest of the three at a none 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 Duluth and Superior, Hermantown, Proctor, Cloquet. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Duluth
The sensors Canairy reads in Duluth are 36 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 |
|---|---|---|
| 1.7 mi NW | 53 | Moderate |
| 1.9 mi WSW | 21 | Good |
| 2.5 mi SSE | 29 | Good |
| 4.7 mi S | 17 | Good |
For most of the year Duluth breathes some of the cleaner air in the region, cooled and scrubbed by the winds off Lake Superior. The hard days come from outside the state: smoke from Canadian and northern Minnesota wildfires drifts down over the lake, and because Duluth sits in Minnesota's far northeast corner it often sees that haze before the rest of the state does.
What Canairy does for Duluth
A clear verdict
Not just a number — a plain-English call for Duluth: 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 Duluth or across the country, on one screen.
What the air in Duluth is doing next
| When | AQI | Expected air quality | Main pollutant |
|---|---|---|---|
| Today | 23 | Good | ozone |
| Tomorrow | — | Good | ozone |
| Monday | — | Good | ozone |
| Tuesday | — | Good | ozone |
| Wednesday | — | Good | ozone |
Wildfire activity across the western U.S. and Canada continues to wind down and smoke-free conditions are expected to continue across our region as we approach the end of summer. Low-level clouds have lingered across the Twin Cities longer than expected on Friday and this has kept ozone lower than was forecast yesterday. However, air quality may still reach the Yellow (Moderate) category across the southern Twin Cities suburbs on Friday. Air quality should remain in the Green (Good) category for the rest of the state. High pressure will build across Ontario on Saturday, and this will produce northeast winds across MN. Cooler and cleaner air will move into the region, and air quality should be in the Green category statewide Saturday. Widespread clouds and scattered thunderstorms will return to the region on Sunday and Monday. Air quality should remain in the Green category statewide through Monday.
Forecast from EPA AirNow for the Duluth Area reporting area. Canairy watches the live sensors against it and tells you when the air actually crosses your threshold, rather than leaving you to check.
Wildfire smoke tends to reach Duluth before the rest of Minnesota
Duluth sits at the tip of Lake Superior, closer to the boreal forests of Ontario and western Canada than any other Minnesota city its size. When those forests burn, the smoke rides the prevailing winds down over the lake, and the Arrowhead is usually under haze while the Twin Cities are still clear. The summer of 2023 made the pattern impossible to miss: the Minnesota Pollution Control Agency issued a string of alerts in May for smoke pushing in from Alberta and Saskatchewan fires, then a statewide alert on June 14, and across May and June much of the Upper Midwest recorded the highest ozone levels ever measured at a regional scale.
The fires do not have to be in Canada to bury Duluth in smoke. In 2021 the Greenwood Fire, sparked by lightning near Greenwood Lake in Lake County, burned from mid-August into October across nearly 27,000 acres of the Superior National Forest, part of an exceptional drought that left the whole Arrowhead tinder-dry. On the worst days smoke season is not a distant story here. It is the air over your own street, which is exactly when a sensor reading a few blocks away is worth more than a statewide forecast.
Lake Superior, the hillside, and air that gets trapped
Duluth is built on a steep hillside that climbs straight up from the water, rising from around 600 feet on Minnesota Point to more than 1,400 feet at the airport on top of the hill. Locals call it the San Francisco of the Midwest for good reason, and that same topography shapes the air. Cold, dense air rolling off Lake Superior can sit under warmer air above it, an inversion that puts a lid on the lower atmosphere and holds smoke, exhaust and wood smoke close to the ground instead of letting it mix out.
The lake also splits the city into microclimates. It can be foggy and cool by the water while it is warmer and clearer up the hill, and the air quality can differ block to block the same way the weather does. A single number for all of Duluth misses that. Checking the sensor nearest you, down by the harbor or up in Piedmont or Hunters Park, tells you what you are actually breathing.
A working port and a wood-smoke winter
The Port of Duluth is one of the busiest on the Great Lakes, moving coal, iron ore, grain, limestone, cement, salt, wood pulp, steel coil and wind turbine parts across its docks. The heavy taconite-processing era that once defined the local economy has faded, with the Duluth Works plant closing back in 1981, but shipping, rail and diesel truck traffic still put particle pollution into the air along the harbor and the industrial waterfront.
Winter brings a quieter, more local source. Duluth winters are long and cold, and plenty of homes lean on wood stoves and fireplaces for heat. On calm, frigid nights, when an inversion parks a lid over the hillside, that wood smoke has nowhere to go and can push neighborhood particle levels up even with no fire for hundreds of miles. It is the kind of pollution that never shows on a regional map but sits right outside your window, and a nearby sensor is the only way to catch it.
Duluth air quality FAQ
What is the air quality in Duluth right now?
As of September 5, 2026 at 7:10 AM CDT, the air quality in Duluth, Minnesota is AQI 21 — Good — with PM2.5 at 3.8 µg/m³, the median of 4 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Is there a smoke map for Duluth?
Yes — the map on this page plots every PurpleAir sensor in and around Duluth in real time, each with its own current reading, out through Superior, Hermantown, Proctor and Cloquet. It is worth knowing what that map measures. A satellite smoke map shows where a plume is drifting overhead, which is not always the same as what is reaching the ground; these sensors measure the fine particles in the air you are actually breathing. In Duluth the two disagree more often than in most places, because the city climbs from the harbor to well over a thousand feet and cool air off Lake Superior can hold smoke down in one neighborhood while it thins out up the hill. Checking the sensor nearest you — down by the water, or up in Piedmont or Hunters Park — tells you more than one number for the whole city.
Why does Canadian wildfire smoke reach Duluth first?
Duluth sits in Minnesota's far northeast corner, closer to the burning forests of Ontario and western Canada than any other major city in the state. When those fires send up smoke, the prevailing winds carry it down over Lake Superior and across the Arrowhead first, so northern Minnesota is often under an air quality alert while the rest of the state is still clear. In 2023 the state's pollution agency issued alerts as early as May for smoke arriving from Alberta and Saskatchewan fires.
Does Lake Superior affect Duluth's air quality?
It does, in two ways. Cold, dense air coming off the lake can slide under warmer air above it and form an inversion that traps smoke and wood smoke near the ground instead of letting it disperse. The lake and Duluth's steep hillside also split the city into microclimates, so it can be foggy and cool by the water while it is clearer up the hill, and the air quality can genuinely differ from one neighborhood to the next.
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 4 curated PurpleAir sensors Canairy tracks in and around Duluth, 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 Duluth
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