Riptides Posing Threat to Beach-Goers : Recreation: Storms of winter have left their mark on the sea floor along the coastline.

As warm days and a mild swell ushered in spring break this week in San Diego, beach-goers turned out in near summer-like numbers. But, after scores of rescues from seasonal rip currents, lifeguards on Wednesday were warning swimmers to be leery of the water.

On Wednesday, San Diego city lifeguards at Mission Beach rescued more than 50 swimmers, body boarders and novice surfers, said Sgt. John Everhart of the central area lifeguard station.

The number of rescues at beaches up and down the coast were high due to strong rip currents that result from sand shifts between seasons. Typically, a rip current is produced when an incoming wave retreats to the area of least resistance, such as a groove or hole in the beach contour, Lifeguard Lt. Marshall Parks said. The rip action is similar to a river running out to sea, Parks said.

“Because of the swells during the winter months, the bottom is ripped up pretty bad,” Everhart said. “It’s classic spring, probably the most dangerous conditions of the year.”

In the central area, which stretches from south Mission Beach to north Pacific Beach, lifeguards rescued more than 200 people during the past three days, Everhart said.

The rescue pace is akin to the busiest days of summer, when beaches are jammed, Everhart said. In the spring, however, only a third of the number of lifeguards are on duty compared to summer, Everhart said. At Mission Beach on Wednesday, five regularly scheduled lifeguards and three extra guards averaged about seven rescues each.

“This is as busy as we get,” he said.

Of the rescues this week, authorities reported one near drowning. A 40-year-old woman visiting from Arizona was pulled from the water Tuesday at Mission Beach, and treated at a nearby hospital.

Cliff rescues above Torrey Pines city beach have also increased as people trying to climb down to the beach have become stranded on poorly marked trails, Lifeguard Sgt. John Little said.

Coastal weather forecasts for the rest of the week call for night and morning low clouds and drizzle, clearing in the late morning, according to the National Weather Service. Highs today and Friday are expected to reach the low 70s.

On the weekend, temperatures up to the mid-80s are forecast, said Frank O’Leary, a forecaster for the National Weather Service.

Unseasonably warm water temperatures created by the El Nino current were also expected to entice beach-goers into the water.

Waters between Ocean and Pacific beaches have recorded temperatures in the mid-60s. In waters off La Jolla, near Scripps Pier, and north to Torrey Pines, temperatures as high as 69 degrees have been reported this week.

Lifeguards had several tips for visitors to the beach.

Currents are strongest at low tide, Pacific Beach lifeguard Chris Farrar said.

“In the afternoon, the tide dropped between 1:30 to 3:30, and the place was on fire,” Farrar said.

Swimmers and other beach-goers are encouraged to ask lifeguards about safe bathing areas. If trapped in a rip current, Parks advised swimmers to swim parallel to shore, which will eventually get them past the rip current, where they can safely head to shore.