East Coast prepares for major heat wave as temperatures reach triple digits

Tens of millions of Americans are under heat alerts as extreme heat hits several parts of the country this week, especially the northeast.

Extreme heat warnings issued for Philadelphia, New York City and Boston go into effect on Sunday as the heat ramps up for the second half of the weekend. An extreme heat watch was also issued for Washington, D.C., and Baltimore on Monday.

New York City Mayor Eric Adams told reporters Saturday that temperatures will reach the high 90s, and peak heat on Tuesday will be 100 degrees.

"The conditions can be deadly and life-threatening if you are not prepared," he said at a news conference.

Zachary Iscol, the city's commissioner of Emergency Management Department, told reporters that the city would be activating its emergency heat plan Sunday and opening 248 cooling centers.

He advised New Yorkers to limit strenuous activities outdoors and to limit their electricity use, including washing machines, during peak power use.

Other parts of the country will also face similar issues due to the high heat.

Heat alerts have been issued from Colorado to Maine, including more than 150 million Americans.

Heat index values in the Midwest will soar into the triple digits this afternoon, with some areas experiencing feels-like temperatures closer to 105-110 degrees. The extreme heat could be life-threatening.

The heat begins expanding east on Sunday with highs soaring into the 90s from the Great Lakes to southern New England. The increasingly humid conditions will make it feel even hotter than that.

Heat index values will hit the triple digits across much of the Midwest again tomorrow, including the Chicago area, with parts of the Northeast seeing feels-like temperatures soaring into the upper 90s to near 100 as well.

Heat relief will be sweeping into the northern Plains over the next 24 to 48 hours as the extreme heat shifts east in the coming days.