Hurricane Erin is causing dangerous rip currents and high surf at beaches along the East Coast, and some areas could see coastal flooding over the coming days. 

The flood risk increases Thursday, when high waves coincide with high tide along the Jersey Shore and New York's south-facing beaches. Waves down the Shore could reach 8 to 13 feet, while the waves on Long Island could hit 10 to 15 feet.

New Jersey Gov. Phil Murphy is urging people to avoid the water, and New York officials shut down several beaches for swimming in New York City and on Long Island. 

From rough surf...

Sea Bright is on a barrier peninsula. The surf was rough Wednesday morning, forcing red flag warnings -- meaning, no swimming allowed. 

"You can come to the beach and hang out on our pavilion deck and whatnot, but you can't go in the water," Chief Lifeguard John Foresman said. "The water will be closed, that's throughout Monmouth County."

Foresman said some surfers might be allowed in the water, depending on their abilities, but the swell is going to be dangerous come Thursday. 

"I've seen it change in the past two days," he said of the water line, adding, "We had the stands about 15 feet closer just two days ago. We had to move them about 20 feet, just because the water line is coming so high."

People were turning out at the beach just to look at the waves. 

"They're, honestly, they're really big. They're insane," Kayla Amato, of Cream Ridge, said. 

Conditions are expected to worsen Thursday, with up to 9 foot swells - a surfer's dream. 

"It's bigger than we get around here. Definitely not something I want to get in the water with, though," Sea Bright resident Jack Madden said. 

... to coastal flooding

Coastal flooding will also be a concern in Sea Bright, which sits between the ocean and two rivers. 

Resident Chriss Kaiser said he won't be going in the water and he's grateful for walls built after Superstorm Sandy that will keep the ocean out of his home. 

"Prior to Sandy, there were large boulders, if you will, but they weren't cemented together. Post-Sandy, they cemented all the stones and they built this, so there's a really nice barrier between the ocean and our homes," he explained. 

He said he's keeping his fingers crossed the Bay Side won't flood. 

"When you have that northeast wind, which is blowing now, it comes up in the streets," Sea Bright resident Roger Rock said. 

"In the past year and a half, they've improved the bulkheads in the back, so hopefully we won't have any river rising, coming through," Cassandra Ferrigno said. 

Click here to check the latest warnings, watches and alerts from the First Alert Weather Team.