A dangerous and prolonged heat wave is expected to build across central and eastern parts of the United States this week, with forecasters warning that temperatures could soar into the triple digits and reach record-breaking levels in some areas into the Fourth of July holiday weekend.

From the Midwest to the East Coast, temperatures are forecast to reach the 90s to low 100s, said Marc Chenard, a meteorologist at the Weather Prediction Center.

Parts of the East, particularly across the Mid-Atlantic and the Northeast, could see temperatures climb above 100 degrees.

“Washington, D.C., will almost certainly exceed 100 on at least one or two days,” Mr. Chenard said. “And Philadelphia and New York City are also currently forecast to go over 100.”

He said daily records could be broken on Thursday and Friday in Washington, New York City and Philadelphia.

Philadelphia could tie its record high of 104 degrees for the month of June.

The heat wave was expected to begin to take hold starting on Sunday across portions of the Plains, where temperatures were expected to rise into the 90s. The heat was expected to reach into the Great Lakes region, including Chicago, and toward the Gulf Coast on Tuesday.

By Wednesday, much of the East Coast is expected to be experiencing the extreme heat.

The high temperatures will be accompanied by high humidity, making conditions feel even more oppressive.

The National Weather Service said that heat index values — a measure of what the temperature feels like to the human body, when humidity is considered with the air temperature — could reach as high as 110 degrees, and locally up to 115.

Little relief is expected during the nights, with temperatures remaining unusually high after sunset.

Mr. Chenard said minimum temperatures were forecast to stay in the 70s, while some cities in the East could remain even warmer, particularly during the middle of the week, which could lead to numerous record-high low temperatures.

“Areas like New York City, Philadelphia and Washington, D.C., could have a low for one or two nights that doesn’t get below 80,” he said. “Chicago could be close to 80 on Tuesday or Wednesday morning, too.”

The hot and humid conditions are expected to last through much of the Fourth of July weekend.

Mr. Chenard said the longevity of the heat was being driven by a “pretty persistent” sprawling area of high pressure, often referred to as a heat dome.

Toward the end of the holiday weekend, the heat dome was expected to shift west, back toward the Plains, allowing for cooler conditions in the East but also for the chance of thunderstorms.