More than 55 million people in the United States have been placed on high alert for an extreme heat wave that is set to sweep across the nation, as temperatures are projected to reach triple digits in several regions. Over the next seven days, approximately 265 million people, accounting for around 82% of the country's population, are expected to experience temperatures exceeding 90 degrees Fahrenheit, coinciding with the start of summer this Thursday.

An Excessive Heat Watch has already been issued for parts of the New England region, including Connecticut, Massachusetts, and New Hampshire. Concord, New Hampshire, in particular, is bracing for scorching heat, with temperatures set to soar to 101 degrees on Wednesday. Meanwhile, New York City is anticipating its first heat wave of the year, with temperatures predicted to reach 90 degrees on Wednesday and a scorching 94 degrees on Thursday and Friday. Pittsburgh is also in for a relentless heat wave, with temperatures expected to surge to 99 degrees from Tuesday through Friday. This could potentially become the hottest June on record for the city, surpassing the previous average temperature high of 96.4 degrees in 1994.

The nation's capital, Washington, D.C., is also expected to be swathed in stifling heat with temperatures approaching 90 degrees, possibly even flirting with the century mark by Friday. Excessive heat warnings are in effect for parts of Ohio and southeast Michigan, where temperatures are expected to remain high from Monday through Friday. Record-breaking temperatures are also predicted for Chicago, Green Bay, and Cleveland, setting the stage for daily temperature records to be shattered in these areas.

Out west, hazardous heat conditions are anticipated for states such as Texas, Arizona, Nevada, and New Mexico. Phoenix and Tucson, Arizona, have already been issued an excessive heat warning, as temperatures threaten to reach a staggering 110 degrees Fahrenheit on Sunday. Roswell, New Mexico, is projected to experience scorching heat at 105 degrees, while El Paso and Fort Stockton, Texas, are also expected to reach similar highs.

Authorities are urging residents to take the necessary precautions to protect themselves from the potentially life-threatening heat wave. Staying hydrated and seeking shelter in cool locations are strongly recommended. Additionally, authorities are encouraging individuals to check on elderly neighbors and relatives who may be more vulnerable to the extreme temperatures.

As the heat wave continues to grip the nation, daily temperature records are expected to be broken in many areas, emphasizing the severity and intensity of this weather event. The entire country is urged to remain vigilant and take necessary steps to stay safe during this unprecedented heat wave.

The article was adapted from information originally reported on abcnews.go.com.