Air Quality in Casper, Wyoming — Live
Live readings from PurpleAir sensors across Casper — with free alerts the moment the air changes, wind or no wind.
AQI 75 from 1 PurpleAir sensor · Trending up · data from PurpleAir
As of , the air quality in Casper, Wyoming is AQI 75 — Moderate and rising — with PM2.5 at 22.0 µg/m³, from 1 live PurpleAir sensor. Canairy's verdict: Mostly clear.
For scale, that PM2.5 reading is about 1.5 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 Casper: weeds pollen is the strongest of the three at a very 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 Casper and Mills, Evansville, Bar Nunn, Glenrock. Every dot is a real sensor, color-coded by current air quality.
Casper's air is good on most days, and the reason is the wind: central Wyoming is rarely still, and that near-constant airflow tends to clear out vehicle exhaust and refinery emissions before they can build up the way they might in a stiller valley. The exceptions are wildfire smoke that drifts in some weeks in late summer and fall — increasingly from fires burning in Canada as well as grass and timber fires closer to home in the Powder River Basin — and the HF Sinclair oil refinery that has operated inside city limits for more than a century.
What Canairy does for Casper
A clear verdict
Not just a number — a plain-English call for Casper: 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 Casper or across the country, on one screen.
Why Casper is usually one of the windier — and cleaner — cities in the country
Casper sits at 5,120 feet on the North Platte River, at the edge of open plains that run for miles in every direction. The city consistently ranks among the windiest in the United States, with average annual wind speeds around 12-13 mph and routine gusts of 40-50 mph, especially in spring, with December typically the windiest month of the year.
That constant airflow is generally good news for air quality. It disperses day-to-day sources — traffic on Interstate 25, the refinery near downtown — before they can concentrate the way pollution does in a wind-sheltered valley. Casper doesn't get the same nightly temperature-inversion buildup that traps smoke and exhaust in mountain-basin towns; the terrain here is too open and the wind too persistent for pollution to sit still for long.
The refinery that's been part of Casper since the oil boom
Casper is nicknamed "the Oil City," and the refinery a few blocks from downtown is not new. Companies began refining crude here as far back as the 1890s, tied to the Salt Creek Oil Field about 40 miles to the north, and the plant now operated as HF Sinclair's Casper Refinery — a roughly 250-acre, fully integrated facility processing about 30,000 barrels of crude a day — is a direct descendant of that history.
In August 2012, the EPA and Department of Justice announced that Sinclair Casper Refining Co. had violated a 2008 Clean Air Act consent decree by exceeding nitrogen oxide emissions limits and failing to properly operate a flare gas recovery system at its Casper and Sinclair, Wyoming refineries. The settlement required roughly $3.8 million in stipulated penalties, about $10.5 million in new pollution control equipment including a selective catalytic reduction system, and combined cuts of about 24 tons a year of NOx, 385 tons of sulfur dioxide, and 59 tons of particulate matter across the two plants — a reminder that the refinery is a real, measured part of what's in Casper's air, wind or no wind.
When wildfire smoke beats the wind
Even Casper's wind can't outrun a big enough smoke plume. In May and again in September 2023, smoke from wildfires burning in Canada settled over central Wyoming for days, dulling the sky and pushing fine-particle readings higher even on days that were sunny and calm at ground level.
The smoke doesn't have to travel that far to matter. In September 2024, air quality in Casper was rated unhealthy after grass and timber fires burning in Campbell and Johnson counties — a couple of hours northeast, in the Powder River Basin — drifted smoke into the city, and by early September 2025 the National Weather Service was again warning of hazy skies and elevated fire danger across central and southern Wyoming. Those are the stretches worth checking a sensor before you commit to an afternoon outside — not the several hundred other days a year when Casper's air is simply clean.
Casper air quality FAQ
What is the air quality in Casper right now?
As of September 15, 2026 at 8:04 AM MDT, the air quality in Casper, Wyoming is AQI 75 — Moderate — with PM2.5 at 22.0 µg/m³, the median of 1 live PurpleAir sensor. Sensitive groups may want to take it slower outside.
Why does Casper's air get smoky some years?
Casper's near-constant wind usually keeps the air clean, but it can't always outrun a big enough wildfire. Smoke from Canadian wildfires reached central Wyoming in both May and September 2023, and smoke from grass and timber fires in Campbell and Johnson counties, roughly two hours northeast in the Powder River Basin, pushed Casper's air quality to unhealthy levels in September 2024. Those weeks are the exception, not the rule.
Does the Casper oil refinery affect local air quality?
Yes, to a measurable degree. The HF Sinclair refinery near downtown has processed crude in Casper for more than a century, and in 2012 the EPA and Department of Justice found the company had exceeded nitrogen oxide limits and mismanaged a flare gas recovery system there, part of a settlement that required new pollution controls and cut combined NOx, SO2, and particulate emissions at its Wyoming plants. Casper's strong, near-constant winds disperse most day-to-day emissions quickly, but the refinery is a real, permitted source worth knowing about, especially if you live close to it.
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 1 curated PurpleAir sensor Canairy tracks in and around Casper, 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 Casper
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