Air Quality in Caldwell, Idaho — Live
Live readings from PurpleAir sensors across Caldwell — with free alerts when smoke, dust, or a winter inversion moves in.
Live Caldwell AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Caldwell and Nampa, Middleton, Parma, Star.
Caldwell's air is calm for most of the year, but the Treasure Valley's bowl-shaped geography makes it change fast in two very different seasons. In summer, smoke from wildfires in Oregon, Idaho, and beyond can drift in and blanket the valley for days at a time, as it did again in late July 2026. In winter, the same mountains that shelter the valley trap cold, stagnant air at the surface, holding wood smoke, vehicle exhaust, and haze in place until a storm finally clears it out.
Canairy watches the sensors around your home, your kids' school, and everywhere else you care about, and tells you in plain English when the air changes enough to matter.
Caldwell sits at the bottom of a bowl
The Treasure Valley is ringed by low mountains and foothills, and in winter the valley floor cools faster than the air above it. That flips the normal order: instead of warm air near the ground rising and mixing pollution away, a layer of warmer air settles on top like a lid and traps the cold, stagnant air underneath. Idaho's Department of Environmental Quality calls this an inversion, and in the Treasure Valley it can last anywhere from a single day to more than a week, breaking only when a strong wind or a cold front finally mixes the layers back together.
Wind under about 5 miles per hour lets an inversion coast along for days, so Canyon County can string together a run of gray, hazy mornings with poor visibility even when there is no fire anywhere near the state. DEQ issues advisories through its Canyon County monitors during these stretches, and it is the same physics that shapes summer haze here: the valley holds onto whatever is in the air, whether that is wood smoke from someone's stove, exhaust off I-84, or a distant fire's plume, until the weather changes.
Wildfire smoke can arrive from fires you never hear about
Caldwell doesn't need a nearby fire to get bad air. In July 2024, the Durkee Fire ignited from a lightning strike east of the Oregon border and grew past 244,000 acres within a week, one of the largest fires in Oregon's history, pushing what Idaho DEQ meteorologist David Luft called one of the most significant, immediate smoke impacts the Treasure Valley had seen in years, even though the fire itself never crossed into Idaho.
That pattern repeated in late July 2026, when smoke settling over the valley got bad enough that Zoo Boise took precautions with its animals during a run of unhealthy air days. Canyon County's location downwind of Eastern Oregon's rangeland and forests means a fire three states away can matter more to Caldwell's air on a given week than anything burning in Idaho, which is exactly why a single regional forecast isn't enough and Canairy reads the sensors nearest to where you actually live.
A church-based air monitor is tracking Caldwell's growth
In September 2023, the Hispanic Access Foundation installed a PurpleAir sensor outside Rosa de Saron Church in Caldwell as part of El Aire que Respiramos, "The Air We Breathe," an EPA-funded project tracking pollution in twelve Latino communities nationwide over three years. The site's local coordinator, Pastor Reyna Ruano, pointed to the reason Caldwell was chosen: "Caldwell is growing. Nampa is growing. Boise is growing. There's so much traffic."
The project exists because the health stakes aren't evenly spread. The Hispanic Access Foundation cites Latino patients as twice as likely to end up in the emergency room for asthma, and Latino children as twice as likely to die from it compared to white children, with farmworkers carrying extra exposure from both field dust and vehicle exhaust along Caldwell's growing commuter corridors. It's one more reason Canyon County now has real sensor coverage instead of a single regional estimate standing in for what an entire county is breathing.
Caldwell air quality FAQ
What is the air quality in Caldwell right now?
This page shows the current AQI for Caldwell, calculated from PurpleAir sensors across the city and updated continuously. The map below shows every live sensor, so you can check the reading closest to your own neighborhood.
Why does Caldwell get smoky in the summer?
Caldwell sits downwind of Eastern Oregon's rangeland and forests, so a large fire two or three states away — like the 244,000-acre Durkee Fire that ignited from lightning in July 2024 — can fill the Treasure Valley with smoke for days without ever crossing into Idaho. Smoke returned again in late July 2026, unhealthy enough that Zoo Boise took precautions with its animals.
What is a winter inversion, and why does Caldwell get them?
An inversion happens when a layer of warmer air settles on top of the cold air sitting in the Treasure Valley, acting like a lid that traps wood smoke, vehicle exhaust, and haze at ground level. The valley's surrounding mountains make this common in winter, and an inversion can last from a single day to more than a week until a strong wind or storm mixes the air back out.
What AQI level is unhealthy?
Under the US EPA scale, AQI 0-50 is Good and 51-100 is Moderate. From 101 the air is Unhealthy for Sensitive Groups - kids, older adults, and people with asthma or heart conditions - and above 150 it's Unhealthy for everyone. Canairy translates these numbers into a plain-English verdict, like whether to close the windows or move a workout indoors.
Where does Canairy's Caldwell data come from?
Readings come from PurpleAir's network of laser particle sensors across Caldwell and surrounding towns, cross-referenced with government monitors and the Google Air Quality API. You can see every sensor behind your numbers on the live map - there's no black box.
Is Canairy free?
Yes. The Canairy app is free to download and includes live air quality for all your saved places, plain-English verdicts, and free push alerts when the air crosses your threshold. A paid plan adds extras like SMS text alerts.
Get Canairy free on Google Play.