Nearly 162 million Americans from 35 states are under extreme heat alerts as deadly wildfires continue to burn in the Western US, with the heat expected to intensify during the week.

Cities in the risk zone include Boston, New York, Philadelphia, Baltimore, Washington, Chicago, Minneapolis, St. Louis, Nashville, Atlanta, Orlando, and Cleveland, according to NBC News, citing the National Weather Service.

The heat is likely to persist across the central US this week, spreading into the Northeast from Wednesday and lasting through the holiday weekend.

Major to extreme heat risk continues, with warm nights limiting relief and raising health risks. Peak heat is expected Thursday-Saturday across the Midwest, Great Lakes, mid-Atlantic, and Northeast, with nearly 100 daily records possibly tied or broken by July 4.

New York City may reach 95F (35C) Friday with a heat index of 106F (41C). Washington and Raleigh, North Carolina, could hit 103F (39C), with heat indexes around 108F (42C) and 107F (42C).

Chicago Mayor Brandon Johnson warned residents Monday to prepare for extreme heat that “can be very dangerous.” The city is under an extreme heat warning until Wednesday, according to Mike Bardou of the National Weather Service.

Meanwhile, wildfires spread across the interior Western US over the weekend, especially in Utah and Colorado. Around 2 million people were under fire alerts Monday across Arizona, Colorado, New Mexico, Utah, and parts of Wyoming, South Dakota, and Nebraska.

Three firefighters were killed on the Colorado-Utah border, US Wildland Fire Service Chief Brian Fennessy said, adding that two other firefighters were injured.

The Cottonwood Fire in southwest Utah has burned over 93,000 acres and remains only 4% contained, according to WatchDuty.com.

More than 50 large fires are burning nationwide, covering over 460,000 acres, according to the National Interagency Fire Center.

Air quality alerts remain in effect across much of Colorado due to wildfire smoke.

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