A late-night rainstorm brought relief to some 400 firefighters struggling to contain the wind-driven flames raging through the community of Seaside Park.
Part of the boardwalk was torn up and a 20ft trench dug to keep flames from spreading through the closely-packed buildings.
Police Chief Francis Larkin said fire chiefs had told him "hot spots" in buildings were slowing containment.
Seaside Park's Town Administrator Robert Martucci said the fire had started in a frozen custard shop and then raced north under winds of up to 40mph.
Governor Chris Christie declared a state of emergency and said about 20 businesses had been affected. The cause of the fire was unknown, and there were some minor injuries, he said.