Wildfires from Canada and the Great Lakes region pushed air quality to unhealthy levels across the Northeast on Wednesday night, turning the New York City sky a faint orange. According to the EPA’s AirNow website, a high-pressure “heat dome” trapped smoke near the ground while pushing temperatures toward 100 degrees across eastern Canada and the U.S.
Air Quality Index Surges in Major Cities
The EPA reported unhealthy air quality levels in several cities by 10 p.m. Wednesday. Minneapolis saw its Air Quality Index (AQI) jump to 287 from 199 in less than an hour. Other readings included New York City at 192, Detroit at 196, and Scranton, Pa., at 157.
The EPA considers readings of 150 or higher “unhealthy” for most people, while levels above 300 are deemed “hazardous.” In Michigan, forecasters noted that visibility dropped below one mile at times, creating hazards for pilots navigating airport descents.
Did You Know? Canada’s weather agency forecasted a “very high risk” for poor air quality through Wednesday night, marking it as a 10 on their 10-point scale.
Heat Dome Impacts and Record Temperatures
A heat dome—a high-pressure atmospheric system—has brought extreme heat to tens of millions of people. The National Weather Service placed nearly 100 million people from the Dakotas to New England under “major” or “extreme” warning levels. Environment Canada issued an orange alert for southern Ontario, the second-highest level in its three-tier system.
The system recently hit the Mountain West, where Salt Lake City recorded 109 degrees. According to official readings, this was two degrees higher than previous records set in 1960, 2002, 2021, and 2022. The Northern Plains have seen consecutive days of daily records.
Minnesota Wildfires and Border Closures
At least 17 wildfires have forced evacuations across Minnesota, according to state officials. Erik Evans, a spokesman for the Minnesota Department of Natural Resources, stated that as of 1 p.m. Tuesday, the five largest fires scorched at least 30,000 acres. He noted that fire officials have not yet contained any of those five fires.
The U.S. Forest Service closed portions of the Boundary Waters Canoe Area in Superior National Forest. The agency reported three active fires inside the Boundary Waters and a fourth that ignited Monday just outside the area. Two of the largest blazes, the Thumb and Bear Trap fires, have crossed the border into Canada.
Potential Weather Shifts and Risks
New York City officials warned of deteriorating air quality on Wednesday, though they noted levels did not reach the dangerous peaks seen in 2023. Forecasters in the New York City weather office said daily records could be set Wednesday unless thickening smoke filters sunlight and keeps temperatures lower.
Meteorologists also warned of “ridge-riding storms” along the heat dome’s northern edge. These thunderstorms form where warm, moist air meets cooler, dry air and can produce hail, tornadoes, and powerful winds. Similar storms in rural Wisconsin earlier this month led to the deaths of three children.
Frequently Asked Questions
What is the current air quality status in New York City?
As of 10 p.m. Wednesday, the EPA’s AirNow website listed New York City’s AQI at 192, which is above the 150 threshold considered “unhealthy” for most people.
How many people are affected by the heat warnings?
The National Weather Service stated that nearly 100 million people from the Dakotas into New England are under “major” or “extreme” warning levels for dangerous heat.
What is a “ridge-riding storm”?
According to meteorologists, these are intense thunderstorms that form along the boundary of warm, moist air and cooler, dry air, potentially causing heavy rain, hail, and tornadoes.
How has the air quality in your city changed over the last 24 hours?