A brutal heat wave scorched a large swath of the U.S. on Wednesday, with millions from the Midwest to the Northeast enduring sweltering temperatures during the Juneteenth holiday.
Cities across the region issued heat advisories warning residents to remain indoors and avoid strenuous activity. In total, more than 82 million people were under some form of heat advisory Wednesday evening.
Boston set a record with a high of 98 on Wednesday, breaking a 1923 record of 96 degrees, according to the National Weather Service. Dozens more record highs are forecast over the next few days.
"It has been a busy day — a lot of different threats throughout the country," NBC News meteorologist Violeta Yas said, adding that sweltering temperatures are expected to continue for several more days.
Cities in New Jersey and Pennsylvania activated city services to keep residents safe. Newark officials declared a “code red” for Thursday and Friday, when the heat index — a measure that combines temperature and humidity levels — could reach 101 degrees.
The Philadelphia health department issued a heat health emergency advisory from Thursday morning through Saturday night, when temperatures could reach triple digits. The declaration activates emergency programs like cooling centers, home visits by specialized field teams and outreach to people experiencing homelessness.
The extreme heat also triggered air quality alerts in Connecticut, Massachusetts, New Jersey, New York, New Hampshire and Ohio.
Forecasts this week have predicted temperatures 10 to 25 degrees above average, soaring into the upper 90s and the low 100s. Heat index readings peaked from 100 to 105 degrees in many locations on Wednesday.
On Thursday and Friday, heavy rainfall and thunderstorms are likely in some areas — eastern South Dakota, parts of Minnesota and western Wisconsin could get excessive rain.
NBC News meteorologist Michelle Grossman warned that extreme heat is not to be taken lightly.
“It is dangerous — extreme heat is the No. 1 weather-related killer, so you need to take it seriously,” she said.
People without access to reliable air conditioning are urged to find places to cool down, as “record warm overnight temperatures will prevent natural cooling and allow the heat danger to build over time indoors without air conditioning,” the National Weather Service said.
Severe heat is also affecting the Southwest, where an excessive heat warning continues for Phoenix and Tucson, Arizona. Last week, a 44-year-old mother from Pennsylvania passed out on a trail in Sedona, Arizona, and died. Her two young daughters and her husband said she appeared to suffer heat exhaustion, according to the Yavapai County Sheriff’s Office.
In New Mexico, firefighters have been battling wildfires that sparked amid dry, hot conditions. At least two people have died and 1,400 structures have been lost in the South Fork Fire and the Salt Fire — blazes that combined have burned over 20,000 acres and prompted evacuations for thousands. As of Wednesday morning, those fires were 0% contained.
Meanwhile, in California, the Post Fire has burned over 15,000 acres across Los Angeles and Ventura Counties and is 39% contained, according to the California Department of Forestry and Fire Protection.
