Air Quality in Pearl City, Hawaii — Live

Live readings from PurpleAir sensors across Pearl City — with free alerts the moment vog or smoke moves in.

Live Pearl City AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Pearl City and Aiea, Waipahu, Waimalu, Mililani.

Most of the year, Pearl City's air is about as good as anywhere in the country. The town sits on the leeward, dry side of Oahu in the rain shadow of the Ko'olau Range, where steady northeast trade winds usually keep the sky clear and keep pollution from settling. The exception comes on a few dozen days a year, when the trades weaken or reverse ahead of a winter storm and vog — volcanic haze from the Big Island's Kilauea volcano, more than 200 miles away — drifts up and settles over leeward Oahu, along with the occasional smoke from a dry-season brush fire in the grasslands just west of town.

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.

Pearl City sits in Oahu's dry, trade-wind shadow

Pearl City sits along the north shore of Pearl Harbor in the Ewa District, on the leeward side of the Ko'olau Range that runs down Oahu's spine. Moist trade-wind air rises and drops its rain on the windward side, over Kaneohe and Kailua, before it ever reaches town — which is one reason Pearl City stays noticeably drier and sunnier than the mountains a few miles east even on an average trade-wind day. Under that normal northeast flow, the same steady breeze that keeps the leeward side dry also keeps its air moving, so pollution rarely has a chance to build up.

That pattern depends on the trades actually blowing, and they blow less than they used to. State climatologist Pao-Shin Chu has tracked Hawaii's trade winds falling from about 291 days a year in 1972 to roughly 210 days more recently, a decline researchers say could add dozens more stagnant-air days across Oahu each year. When the trades stall or reverse into a southerly Kona wind, the sea breeze that normally scours the Ewa Plain clean stops doing its job.

Vog from a volcano 200 miles away reaches Pearl City

Kilauea, on the Big Island, is normally shielded from Oahu by the trade winds, which carry its sulfur dioxide plume southwest toward the Kona coast instead. But a 2017 study counted roughly 101 vog days a year reaching Oahu, arriving in about 57 separate events that typically lasted one to two days apiece. The riskiest setup is a pre-frontal Kona wind ahead of an approaching cold front, when the trades die, an inversion layer settles low, and southerly winds carry the vog plume back up the island chain into Honolulu and the Ewa side, including Pearl City.

The clearest recent example was the 2018 Lower Puna eruption, when Kilauea's sulfur dioxide output jumped from a baseline of roughly 1,500 to 2,500 tons a day to as much as 40,000 tons on its worst day, May 30, 2018. Oahu felt it: the EPA stood up a 35-monitor tracking network that June, and a University of Hawaii economic study the same year found emergency-room visits for breathing problems rose 23 to 36 percent during vog events. It's a reminder that Pearl City's air can turn hazy without a single local source doing anything different — the volcano is doing the polluting from across the ocean.

Dry-season brush fires add smoke of their own

Pearl City's dry season, roughly May through October, is also brush-fire season in the grasslands just west of town. In August 2025, a fire burned through more than 250 acres near Kunia Camp, bordering Waipahu, which shares Pearl City's western edge, and a second blaze the same month burned about 600 acres nearby and briefly closed Kunia Road. Hawaii's Department of Land and Natural Resources warned that smoke could linger for days or even weeks as smoldering stumps kept burning after the flames were out.

The fuel is invasive guinea grass, which the state's own invasive species program rates as a high fire risk: it grows fast, dries out completely between rains on the leeward side, and regrows even thicker after a burn. None of this reaches Pearl City's rooftops directly, but it sits close enough that a dry, windy afternoon in Kunia or Waipahu can put a haze over the Pearl Harbor side of town before anyone smells smoke.

Pearl City air quality FAQ

What is the air quality in Pearl City right now?

This page shows the current AQI for Pearl City, 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 vog sometimes reach Pearl City?

Pearl City is normally shielded from Kilauea's volcanic haze by steady northeast trade winds, which carry the plume toward the Big Island's Kona coast instead. But when the trades weaken or reverse into a southerly Kona wind, usually ahead of a winter cold front, the vog can drift back up the island chain and settle over leeward Oahu, including Pearl City. A 2017 study counted roughly 101 such vog days a year on Oahu.

Does Pearl City get wildfire smoke?

Not from forest fires, but from brush fires in the dry grasslands nearby. In August 2025, fires burned more than 250 acres near Kunia and about 600 acres in a separate blaze close to Waipahu, right on Pearl City's western border, with officials warning smoke could linger for days afterward. Central and leeward Oahu's dry season, roughly May through October, is when that risk is highest.

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 Pearl City data come from?

Readings come from PurpleAir's network of laser particle sensors across Pearl City 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.