Heat Dome: Triple-Digit Temperatures and Heat Alerts Blanket Eastern US

A relentless heat wave continues to scorch the eastern half of the United States, with temperatures expected to peak on Tuesday and dozens of new record highs possible across a vast swath of the country. Nearly 160 million people are under heat alerts from eastern Texas to Maine, as temperatures are forecast to be up to 20 degrees Fahrenheit above seasonal averages. Triple-digit highs are possible along the East Coast, with temperatures in New York City and Washington, D.C., rivaling Death Valley in California. Temperatures over 95 degrees will be widespread across the central and eastern United States, and heat index values—a measure of what conditions “feel like” when humidity and air temperatures are combined—are expected to be well into the triple digits throughout the region, with some places possibly reaching as high as 115 degrees. The multiday heat wave, which began over the weekend, has already proven deadly: A woman in St. Ann, Missouri, died Monday of heat-related causes, according to the city’s police chief, Aaron Jimenez. She died in her home after having no water or air conditioning for at least three days, Jimenez told NBC News. In Paterson, New Jersey, more than 100 people needed treatment during two outdoor graduation ceremonies Monday as the heat index climbed to 107 degrees. Monday evening, Mayor André Sayegh declared a state of emergency due to the high heat and canceled all recreational activities. More than 60 record-high temperatures were set across the country on Monday, with more expected this week from the Southeast into New England. Preliminary daily records were set on Tuesday in New York City (which hit 99 degrees), Philadelphia (which reached 100 degrees for the first time since 2012), and Raleigh, North Carolina (which hit 100 degrees). New all-time June monthly records were set in Boston (101 degrees) and Providence, Rhode Island (100 degrees), and Newark, New Jersey, tied its June record of 103 degrees. Conditions are expected to remain stiflingly hot through the evening hours, according to the National Weather Service. “Overnight lows are forecast to only drop into the 70s, with urban centers along the East Coast struggling to drop below 80 degrees at night,” the weather service said on Tuesday in its short-range forecast. The sweltering conditions are caused by a high-pressure ridge that is parked over the eastern United States. Such systems are known as heat domes because they trap hot air over a region, driving up temperatures for prolonged periods. While some relief is expected later this week, heading into the weekend, heat and humidity will continue to soar in the coming days. “The most significant cumulative heat impacts are anticipated across the Mid-Atlantic through Thursday and eastern Ohio Valley into Friday, leading to several consecutive days of oppressive heat,” the weather service said. Anyone is susceptible to heat-related illness or death, but excessively hot and humid conditions—especially for days on end—are particularly risky for children, people with pre-existing health conditions, older adults, and individuals who work outdoors. These health impacts are a significant concern as heat waves become more frequent, intense, and longer-lasting due to climate change.