PHILADELPHIA (WPVI) -- The birthplace of the nation is celebrating the Fourth of July and America's 250th birthday as festivities kick into high gear in Philadelphia.
However, extreme heat is forcing many event cancellations.
An Extreme Heat Warning remains in effect for the entire Philadelphia region. Temperatures in the city are expected to be around 100 degrees through Saturday.
For the latest forecast, visit 6abc.com/Weather.
Meanwhile, ABC is marking America's 250th anniversary with 24 hours of unparalleled programming called "Disney Celebrates America."
"World News Tonight" anchor David Muir kicked off ABC News' celebration of America's 250th birthday by climbing up through Lady Liberty's right arm to reach the torch, standing over 300 feet in the air.
Holiday weekend celebrations along the Jersey shore drew packed beaches, busy boardwalks and early fireworks as visitors welcomed the start of the Fourth of July festivities.
America's birthday weekend began with a bang, with spectators dressed in red, white and blue gathering for a pre-fireworks concert in Stone Harbor. Jim Bannach and the BLT Orchestra performed.
Angela Shaw of Ocean City and Bannach's girlfriend said the patriotic atmosphere moved her.
"It's heartwarming. I was raised in a very patriotic family - veterans, my dad was a veteran. It just brings tears to your eyes," she said.
For Nancy Stutzman, who shares a birthday with the nation, the holiday has long been a special tradition. And for her husband, Tom Stutzman of Williamsport, it allows for an easy birthday gift!
"I always got her the fireworks and the band," he said.
Nancy Stutzman recalled celebrating the country's bicentennial decades ago.
"It's great, I remember years ago when we celebrated 200 in Williamsport - there was a huge parade and we had just gotten married," she said.
In Wildwood, the boardwalk's nostalgic pull brought back longtime visitors. Angie DeRolf of Mullica Hill returned for the first time in 60 years.
"It's changed a lot for the good," she said.
Despite the heat, crowds continued to grow through the afternoon. David Fessler of Wildwood said he expects the holiday to get even busier.
"It's gonna be a crazy weekend. Got fireworks going off all over the place tonight, tomorrow. Parking, oh my God, we had to park I don't even know how many blocks," he said.
For one couple, July 3 turned out to be especially memorable. Moments after getting engaged on the Wildwood boardwalk, Gary Bennett and Alicia Galat of Broomall reflected on the significance of the place.
"We both have been going to Wildwood ever since we were kids, even before we met," Galat said.
Fireworks are planned across nearly every shore town on July 4, and with another hot day expected, beaches are likely to be crowded again as celebrations continue.
Due to the extreme heat and hazardous weather conditions, the Marple Newtown 4th of July Parade is canceled, officials announced on Friday night.
Security measures are increasing across Philadelphia as America's 250th birthday gets underway and officials prepare for large crowds ahead of the Fourth of July.
Barriers, cameras and a visible law enforcement presence have been deployed around historic sites throughout the city. The security operation includes multiple agencies working together, including Philadelphia police, counterterrorism units, U.S. park rangers, SWAT teams and police departments from surrounding counties.
Visitors said the heightened security was noticeable.
"It's great seeing the security; I've seen police officers out there," said Perry Loskamp of Long Island.
Officials say large-scale public events require extensive planning because they can be attractive targets for potential attackers.
"Our foreign adversaries who would love to embarrass the United States while it's celebrating its birthday," said Don Mihalek, a retired senior Secret Service agent.
Mihalek said there are no specific credible threats to the events but noted that security officials remain alert to a range of potential risks.
"But they are tracking a lot of threat activity, generally speaking from foreign state actors, lone wolf actors who look at mass gathering events as targets of opportunity," Mihalek said.
People visiting the city said they welcomed the visible security presence during the celebrations.
"It makes me feel safe seeing all the security," said Jennifer Schock of San Diego.
"I don't feel uneasy. It's a positive police presence," said Jay Smith of Old City.
Officials are encouraging attendees not only to feel safe but also to remain vigilant and report any suspicious activity.
"I'm not too worried. I'm not too concerned, but I am aware, very aware," said Shawn Coleman of Old City.
As the holiday festivities continue, law enforcement agencies will maintain a heightened presence throughout celebration areas while urging the public to stay alert and enjoy the events safely.
