New York, Jun 29 (IANS): Millions of people across the US are facing severe weather, with parts of the country smothered by smoke from Canadian wildfires, while others face stifling heat and severe storms.

Around 87 million people are at risk for poor air quality due to smoke from the Canadian wildfires, with Detroit, Chicago and Minneapolis among the top four cities with the worst air quality in the world, according to the tracking service IQAir.com.

New York Governor Kathy Hochul expanded the air quality health advisory on Wednesday to include the entire state as she announced that her office will use, for the first time, emergency cell phone alerts to inform residents if the air quality index passes the threshold for "very unhealthy" air for more than an hour, Xinhua news agency reported.

"With smoke from the Canadian wildfires once again impacting air quality throughout our state this week, we're urging New Yorkers to remain vigilant," the Governor said in a statement. "We're activating emergency cell phone alerts to ensure New Yorkers have the latest information and are continuing to coordinate with local counties to monitor conditions and distribute masks."

Meanwhile, "around 69 million people face heat alerts, which expanded to include not only the South and the Southeast, but also the Midwest and California", reported NBC News.

Severe storms capable of large hail are also anticipated across parts of Minnesota and Wisconsin, with Minneapolis being the largest metro area at risk, according to the report.

The recent severe weather has prompted major disruptions, including sweeping flight cancellations and delays numbered at thousands, it noted.