On the Ocean City beach, conditions were nearly as brutal as on the mainland. At the water's edge, the temperature was over 90 degrees at midday and the sea registered an unseasonable 72 degrees, according to a local surfing report.
In Atlantic City, the ocean was 70.2 degrees, and at Cape May it was a freakish 76.8 degrees, according to the National Oceanographic Data Center, operated by the National Oceanic and Atmospheric Administration. Water temperatures in the mid-Atlantic are usually in the 60s during June, according to the agency.
Relief from the heat brought many to the resort's Ninth Street Beach, which was covered towel-to-towel with sunbathers.
"It looks like August, it really does," said lifeguard Matt Betson, 26, a member of the city's beach patrol for 10 years. "It's normally not this crowded on a weekday in June, not until the season really kicks in."
Those who ventured into the ocean, whether in a cautious tiptoe or a full-throttle run, were pleasantly surprised.
"I can never remember [the water] being this warm this early," said Ed Miller, 67, down for the day from Laurel Springs.
Sandra Miller, whose family has a summer home in Margate, had brought her four children to town in search of a guarded beach. Margate begins full coverage on Saturday.
"Nobody usually wants to go in the ocean this time of the year, so we usually don't have to worry about it," said Miller, of East Greenville, as she bounced her 11-month-old son Archer, in the shallows.
While some beaches in the city already were scheduled to have guards, the favorable conditions prompted officials to add more locations, according to Michele Gillian, executive director of the Ocean City Regional Chamber of Commerce.
"We are prepared and open," Gillian said. "We want to put safety first for our visitors."