It’s extra sunny in Philadelphia this weekend and hot and humid weather is settling over the City of Brotherly Love as tens of thousands of delegates are about to converge on the city for the Democratic National Convention.

The heat wave is expected to gain momentum this weekend and peak Monday, the convention’s first day, with temperatures possibly hitting 100 degrees, said Mitchell Gaines, meteorologist with the National Weather Service in Mount Holly, New Jersey.

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. Some New England areas are under severe thunderstorm warnings.

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

Coupled 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. Officials also warned of the danger of thunderstorms, which began lashing the city 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 would also 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.

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. “We got all these air conditioners working, they’re closing it in.”

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.

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.

(AP)