Air Quality in Fort Collins, Colorado — Live
Live readings from PurpleAir sensors across Fort Collins — with free alerts when summer ozone or foothills wildfire smoke moves in.
AQI 64 from 5 PurpleAir sensors · Trending up · data from PurpleAir
As of , the air quality in Fort Collins, Colorado is AQI 64 — Moderate and rising — with PM2.5 at 16.2 µg/m³, the median of 5 live PurpleAir sensors reading 60 to 89. Canairy's verdict: Mostly clear.
For scale, that PM2.5 reading is about 1.1 times 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 Fort Collins: weeds pollen is the strongest of the three at a high 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 Fort Collins and Loveland, Windsor, Wellington, Laporte. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Fort Collins
The sensors Canairy reads in Fort Collins agree right now — all 5 sit in the Moderate band, a 29-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 1.3 mi ENE | 63 | Moderate |
| 1.4 mi NW | 65 | Moderate |
| 3.1 mi WNW | 60 | Moderate |
| 4.3 mi N | 89 | Moderate |
| 5.0 mi ENE | 71 | Moderate |
Fort Collins sits right where the plains meet the Rocky Mountain foothills, and most days that geography works in the city's favor — clean air moving off the mountains, no heavy industry nearby. The exceptions are real and predictable: hot, sunny summer days build ground-level ozone across the whole northern Front Range, and the forests just west of town, up the Cache la Poudre canyon, have produced two of Colorado's largest wildfires since 2012.
What Canairy does for Fort Collins
A clear verdict
Not just a number — a plain-English call for Fort Collins: 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
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Fort Collins shares the Front Range's ozone problem
Larimer County, Fort Collins included, is part of the Denver Metro/North Front Range ozone nonattainment area under the EPA's 8-hour standard — the same designation that covers Denver, Boulder, and Weld counties. The Regional Air Quality Council, the multi-county body that coordinates the area's ozone response, states it plainly: ground-level ozone is Larimer County's most pressing air quality issue, and it is a warm-season problem, building on the hottest, sunniest days roughly from May through September.
Ozone doesn't come out of a smokestack — it forms when vehicle exhaust and emissions from oil and gas wells in the Denver-Julesburg Basin to the east, in Weld County, react in strong sunlight. Fort Collins sits close to 5,000 feet, where thinner air lets more UV through, so the same load of traffic and drilling emissions cooks into ozone faster than it would at sea level. RAQC runs a standing Oil & Gas Technical work group for exactly this reason — the wells feeding Colorado's Front Range corridor are a recognized part of the region's ozone math, not just the cars on I-25.
The foothills west of town have burned twice in under a decade
In June 2012, lightning sparked the High Park Fire above Buckhorn Road in the Roosevelt National Forest, directly in the mountains west of Fort Collins. It burned for three weeks, consumed 87,284 acres, and destroyed 259 homes — at the time the second-largest wildfire in Colorado history. It was a preview of what the same stretch of forest would do eight years later.
The Cameron Peak Fire ignited near Chambers Lake in August 2020 and burned for 112 days, eventually covering 208,663 acres to become the largest wildfire in Colorado history. It crept to within roughly 8 miles of Horsetooth Reservoir, and on its worst days the smoke was thick enough to block out the sun over both Fort Collins and Estes Park, with a pyrocumulonimbus cloud towering over the city. That same autumn, the East Troublesome Fire exploded across the Continental Divide toward Estes Park, so for several weeks in October 2020 Larimer County was dealing with major smoke from two directions at once.
Laporte and the Poudre Canyon are the city's smoke gateway
The Cache la Poudre River comes out of its canyon at Laporte, just northwest of Fort Collins, right where the forest meets the plains. That canyon corridor is also where High Park and Cameron Peak both burned, so when a fire is running in that country, Laporte and northwest Fort Collins tend to see and smell smoke first, before it spreads across the rest of the city.
The same downslope winds that give Fort Collins its frequent warm winter spells — Chinook-type gusts dropping off the Rockies — can also fan a fire in that canyon and, on other days, help push accumulated smoke or haze out of the area. It's the same geography working two different ways depending on the day, which is why a single citywide number is a rougher guide here than sensors placed close to where you actually live.
Fort Collins air quality FAQ
What is the air quality in Fort Collins right now?
As of September 14, 2026 at 9:38 AM MDT, the air quality in Fort Collins, Colorado is AQI 64 — Moderate — with PM2.5 at 16.2 µg/m³, the median of 5 live PurpleAir sensors. Sensitive groups may want to take it slower outside.
Why does Fort Collins get bad ozone days in the summer?
Fort Collins and the rest of Larimer County are part of the Denver Metro/North Front Range ozone nonattainment area. Ground-level ozone forms when vehicle exhaust and emissions from Weld County oil and gas wells react in strong sunlight, and Fort Collins' near-5,000-foot elevation means more UV gets through, speeding up that reaction on hot, still days roughly between May and September.
Has wildfire smoke ever been a serious problem in Fort Collins?
Yes. The Cameron Peak Fire in 2020 — the largest wildfire in Colorado history — burned in the mountains about 8 miles from the city and blotted out the sun over Fort Collins on its worst days. The High Park Fire in 2012 burned even closer, igniting directly west of the city above Buckhorn Road. Both fires started in the forest that the Cache la Poudre River flows out of at Laporte, just northwest of town.
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 Fort Collins, 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 Fort Collins
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