PHILADELPHIA (AP) — As thousands of delegates arrive in Philadelphia for the Democratic National Convention, it’s not just politics they have to contend with — it’s also the hot and sticky weather.

The heat wave that descended on the city is expected show no mercy on Sunday with temperatures around 96 degrees. It could peak on Monday, the convention’s first day, with temperatures possibly hitting 100 degrees, said Mitchell Gaines, a meteorologist with the National Weather Service in Mount Holly, New Jersey.

READ MORE: Supreme Court Overturns Roe v. Wade, Allowing States To Ban Abortion

Many parts of the United States are experiencing higher than normal temperatures — like most of the Midwest — but the Philadelphia area is slated to be the hardest hit in the Northeast. Other parts of the region, including New York City, are in heat advisories. And the higher temperatures have brought powerful thunderstorms to some New England states, rain knocking out power to tens of thousands of residents.

In Arizona, where temperatures hit 112 on Friday, a 12-year-old boy died after becoming ill after a hike.

READ: Security Closures Begin Ahead Of DNC

Along with the considerable amount of humidity, the heat index in the Philadelphia area could be pushed as high as 108 on Monday, Gaines said. Highs in the mid- to upper-90s are expected each day through Wednesday.

“The multiple days of excessive heat will greatly affect those who are attending outdoor activities, especially events with large groups of people that are gathering in the direct sun,” the weather service said. Officials warned that in urbanized areas such as Center City Philadelphia, even nighttime temperatures may not drop below 80, especially Monday night. There also is the possibility of thunderstorms, such as the brief one which lashed Philadelphia during the late afternoon and evening on Saturday

To protect thousands of demonstrators expected during the July 25 to July 28 DNC, Philadelphia officials said two medic tents and two “misting” tents would be set up and water would be distributed. Medics also would be assigned to take part in marches.

Workers preparing for the convention and others in downtown Philadelphia on Saturday afternoon were trying to keep cool.

Latest Forecast

READ MORE: Supreme Court's Roe v. Wade Decision Garners Strong Reactions In Philadelphia: 'It's Taking Away Basic Women's Rights'

Will Adams, 69, of Pennsauken, New Jersey, stood next to a gigantic air conditioner under tents being erected outside the Comcast Center for a DNC event. He and the crew were putting up speakers and television screens as security fences were going up outside. He couldn’t help but think wistfully about the mild weather during similar preparations for the papal visit last September.

“That was good weather then,” he said.

Chris O’Brien, 36, of Flourtown, Pennsylvania, stood by a spray park — a public water play site — rocking his 2-month-old, Maeve, who was sleeping under the shade of a towel. He was waiting for the rest of his family while he watched former Philadelphia mayor Michael Nutter a few yards away, in a suit, shooting a CNN panel broadcast.

READ: Dems Bring The Heat For DNC

O’Brien said he and his family planned to spend a lot of time in air conditioning for the next few days.

“Libraries, the mall … and we were thinking about going to the Please Touch Museum or the Franklin Institute. Whatever there is to do inside, we’re doing it,” he said.

Avere Scurry, 21, sitting behind the cash register at a pop-up beer garden across near the Philadelphia Museum of Art and its famed “Rocky” steps, said staff members were taking precautions in the heat.

“It’s not easy, but we have umbrellas so that helps. We have water. There’s a trailer over there that’s air conditioned … so every couple of minutes we’ll rotate and we’ll sit in the air,” Scurry said.

MORE NEWS: Roe v. Wade Overturned: These US Companies Will Cover Travel Costs For Employees Who Need Abortion

(Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)