A lengthy and potentially dangerous stretch of extreme heat is expected to sweep across a large portion of the central and eastern United States this week, according to the National Weather Service. Temperatures are on the rise heading into the July Fourth holiday, and high humidity arriving alongside the heat will make conditions feel significantly worse than the thermometer alone suggests.
As of Sunday, parts of the country — particularly Phoenix, central Texas, and much of the Southwest — were already recording temperatures near 100 degrees Fahrenheit (38 degrees Celsius). The weather service also issued warnings about rapidly developing wildfire conditions across much of the West, where new fires were breaking out across the region.
More than 130 million Americans across southern and Great Plains states were already under moderate to severe heat risk conditions on Sunday, according to weather service maps. That affected area is expected to grow and intensify as the week continues.
Forecasters are predicting several consecutive days of extreme temperatures — some topping 100 degrees F — settling over the lower Great Lakes, the mid-Atlantic region, and the Mississippi and Ohio River valleys. Weather service meteorologist Bryan Putnam said some record high temperatures could be broken in areas stretching from the lower Great Lakes through the mid-Atlantic and into New England later in the week.
Several major cities may record their hottest temperatures of the year so far, even as they host World Cup matches and celebrations marking America’s 250th anniversary. East Coast cities including New York, Philadelphia, Washington, and Baltimore are expected to feel the brunt of the heat, along with Midwestern and Great Lakes cities such as Chicago, Indianapolis, St. Louis, and Detroit. Southern cities including Dallas, Little Rock, Arkansas, and Memphis, Tennessee, will also face dangerous heat conditions.
The heat is forecast to linger into next weekend across the Great Plains, the Southeast, and the mid-Atlantic, the weather service said. Temperatures are expected to climb well into the 90s and low 100s Fahrenheit, with heat indexes — which account for humidity — reaching between 100 and 110 degrees F (40 to 43 degrees Celsius), and potentially as high as 115 degrees F (46 degrees Celsius) in some locations.
Putnam stressed the broad danger this heat poses. “That’s heat that’s impactful to anyone,” he said. “It’s not just older adults or younger children or people who are spending a ton of time outdoors, maybe straining themselves a little more than normal. This is heat that really could impact everyone, especially with people outdoors going into the holiday weekend.”
AccuWeather meteorologist Tyler Roys noted that temperatures will run significantly above seasonal averages. In Washington, for example, temperatures around July Fourth typically average around 89 degrees F (32 degrees Celsius), while Indianapolis averages around 85 degrees F (29 degrees Celsius). This week, both cities are expected to run 10 to 11 degrees hotter than those averages, Roys said.
Roys described the high-pressure system driving the heat as acting like a “rock” that forces storms around it and cuts off rainfall across the East — a pattern sometimes referred to as a “heat dome.” Overnight temperatures dropping only into the 70s F or even the high 80s will offer little relief, meteorologists said.
For people without air conditioning, particularly in East Coast cities like New York where nighttime lows may not fall below 80 degrees F (27 degrees Celsius), Roys said sleeping will be miserable. He also warned that this is a prime time for heat-related illness, because the body has no opportunity to recover and cool down overnight.
The National Weather Service advises people to reduce outdoor activity during peak heat hours, drink plenty of water, and make sure they have access to air conditioning or other cooling locations.
Meanwhile, wildfire conditions remain severe across the West. Three firefighters working for the U.S. Wildland Fire Service and the U.S. Forest Service were killed near the Colorado-Utah border when fast-moving flames overtook them. Two other firefighters sustained burn injuries in the same incident. Wildfire activity has been intensifying across Utah, Colorado, Arizona, and other parts of the Western U.S. as hot, dry, and windy weather continues to fuel the blazes.
