An extremely dangerous heat wave is underway for the eastern half of the United States as a potent heat dome reaches its peak, bringing the hottest temperatures of the year so far – the hottest in years for some cities – and putting tens of millions at risk.
Over 250 daily temperature records could be broken during the peak of the heat on Monday and Tuesday, including both record highs and record warm lows. Temperatures in some locations from Philadelphia to Boston could be the hottest in any month in over a decade. Additional records could fall Wednesday and Thursday.
Around 150 million people are under heat alerts Monday, according to the National Weather Service. It feels more like July, summer’s hottest month, than June for many locations as temperatures rise 15 to 20 degrees above normal.
A level 4-of-4 extreme heat risk is in place through at least Thursday, stretching from the Midwest to the Mid-Atlantic and including some parts of the Northeast. This long-lasting heat is rare and will likely offer little to no overnight relief, the NWS cautions.
Heat-related illnesses increase significantly during extreme heat and can be life-threatening, especially for children, the elderly and people with pre-existing health conditions.
The dangerous impacts were immediate as sizzling conditions ramped up in the central US over the weekend. Multiple people, including a Major League Baseball player, an umpire and a staff member, were treated for heat-related illnesses Saturday when the Seattle Mariners faced off against the Chicago Cubs at Wrigley Field in Chicago. Temperatures spiked into the mid-90s during the game but humidity made it feel more like 105.
The hazardous heat spread into the East on Sunday and will reach a fever pitch Monday and Tuesday.
Heat remains the deadliest form of extreme weather in the US, and the frequency and longevity of extreme heat waves are on the rise in recent years due to human-caused climate change. Nighttime temperatures are taking the hardest hit from climate change, and are warming faster than daytime highs.
Nearly 100,000 homes and businesses were without power in Ohio, Pennsylvania, New York and New Jersey amid the dangerous heat Monday afternoon, according to PowerOutage.us.
Extreme heat also takes a toll on infrastructure, causing materials like concrete and asphalt to expand and warp. Problems were already cropping up in the Midwest over the weekend; parts of key thoroughfares in Milwaukee and Green Bay, Wisconsin, suburbs were closed after buckling under searing heat Sunday, local officials said. Similar scenes unfolded in Cape Girardeau, Missouri, and the city warned more streets could crack as the heat persists.
The skyrocketing temperatures have implications for rail and air travel, too. Trains powered by electrified wires typically have to run slower than usual as the heat makes the wires sag, leaving them susceptible to damage. Some Amtrak travelers in the Mid-Atlantic and Northeast could experience delays Monday due to “temperature-related speed restrictions,” the company said on X.
Brutally hot days can also make takeoffs harder for aircraft: Hot air is less dense than cool air, making the lift needed to send a plane into the air harder to achieve.
The temperature in New York City tied its daily record of 96 degrees Monday afternoon – the hottest day the city has had since August 2022. Tuesday’s high will likely break the daily record: It could reach 100 degrees. The city hasn’t seen that temperature in June since 1966. The last time New York City hit 100 was on July 18, 2012.
Other I-95 corridor cities are roasting this week. Philadelphia will hover within a degree or two of 100 through Wednesday. On Monday, the city hit a new high temperature record for the day and additional daily records will likely fall on Tuesday and Wednesday. Tuesday’s high of 101 degrees could come close to the hottest June day on record for the city and would mark the highest temperature recorded since 2012.
Boston could set a record for hottest temperature in the month of June, and come close to its all-time high, with 102 degrees forecast for Tuesday.
Washington, DC, will endure a trio of triple-digit days Monday through Wednesday, likely breaking multiple daily high temperature records along the way. The nation’s capital doesn’t typically record its first 100 degree day until mid-July.
Not even northern New England is escaping the intense heat. Monday became one of the three hottest June days on record for Burlington, Vermont, when the temperature hit 97 degrees in the afternoon. The city – located fewer than 40 miles from the Canadian border – typically doesn’t see that happen until mid-July, if heat reaches that level at all.
Temperatures will slowly start to ease on Wednesday, especially for some in the Midwest and New England, but Thursday will mark the true turn back toward more normal June warmth for many in the eastern half of the country.
This early-season event is likely just a snippet of what’s to come.
For nearly the entire Lower 48 — excluding parts of Arizona, New Mexico and West Texas — the warmest days typically occur in July or August. Plus, a hotter than normal summer is expected for the entire Lower 48, according to forecasts from the Climate Prediction Center.
CNN’s Chris Boyette and Tyler Ory contributed to this report.