Big crowds came out to the shore Saturday in Sandy Hook while temperatures climbed into the 90s.
Lines had formed at the toll booths just as the park opened. Authorities say they reached capacity just after noon.
Beachgoers were advised to bring a tent or an umbrella along with sunscreen and water, as well as something on their feet as they are walking on the hot sand.
Amid the extreme heat, health officials are also advising people to limit their activity and to check on friends and family members who may not have access to air conditioning.