It's the time of year when the sounds of crickets, lawn mowers and ice cream truck jingles fill the air. But at Peninsula Regional Medical Center in Salisbury, summer is marked by the whir of medevac helicopters.
"It's trauma season," said Kari Cheezum, the hospital's trauma program manager.
Nearby Ocean City is coming off a dangerous summer for beachgoers. Town lifeguards summoned ambulances an average of more than once a day last summer, more than twice as often as a year earlier, according to the Ocean City Beach Patrol. Three people drowned, a higher fatality count than officials usually see.
But there are reasons to believe this summer will be safer. A year ago, tons of sand had been freshly pumped onto Ocean City beaches, an anti-erosion measure that can allow waves to crash on shore with injurious force, but sandbars have since returned to a more natural shape. If forecasts of a quiet hurricane season come to pass, that could mean fewer storms churning up rough surf and rip currents.
As the beach season kicks off this busy Memorial Day weekend, Ocean City officials expect to host millions of visitors over the next three months.
While they don't have specific projections for the whole season, officials expect up to 250,000 visitors this weekend, said Jessica Waters, communications manager for the Town of Ocean City. The town usually averages 200,000 to 250,000 visitors on summer weekends, peaking on the Memorial Day and Fourth of July holidays.
"After a long and harsh winter, a lot of people are looking forward to the summer season, and for many people, summer includes the beach," Waters said. "We expect a big Memorial Day weekend and summer season."
Town officials are ready to keep the beachgoing hordes safe but urge people to be cautious when venturing into the waves.
"With the thousands of people who go in the water, there's going to be accidents," Mayor Rick Meehan said. "We can really minimize those by paying attention to the lifeguards and really watching the surf conditions."
Ocean City lifeguards made 118 "urgent" calls for ambulances last summer, up from 54 the previous year and the most since 2011. Those calls are for severe injuries that often have the potential to be life-threatening, including head, neck and back injuries, and heart attacks, said Capt. Butch Arbin of the Ocean City Beach Patrol.
And while the Beach Patrol does not compile statistics on drownings — in most summers, there is usually one, if any, Arbin said — last summer was an anomaly. Two teenagers drowned within a two-week span in June, and a third drowned in August when he was caught in a rip current 40 minutes after lifeguards went off duty.
Multiple drownings had not occurred in Ocean City since 2006, when a Columbia man and his 15-year-old daughter died as he tried to rescue her from a rip current. And drownings rarely occur while lifeguards are on duty, Arbin said. A 19-year-old Morgan State University student drowned in a rip current in 2007 while lifeguards were on duty.
Arbin said there were extraordinary circumstances in each of last summer's drownings — a medical emergency, alcohol and low swimming ability were among the factors involved, he said.
Unusually rough waters were also an issue throughout much of the summer, stirring up strong rip currents, channels of water that can pull swimmers rapidly away from the shore. Lifeguards made nearly 2,700 rescues, up about 700 from the previous year but fewer than the 2,900 in 2012. In many cases, rescues are considered preventive, and the swimmers say they weren't aware they were in danger, Arbin said.
At Peninsula hospital, where many trauma victims from Ocean City are taken, Cheezum said the staff noted an uptick in serious injuries last summer, though she did not have precise statistics. Common emergencies include spinal injuries, dislocated hips, rib fractures and collapsed lungs, suffered when waves throw people into the sand.
Swimmers were restricted to knee-deep water in late August as Hurricane Cristobal stirred waters off the coast. Lifeguards blamed such storms for both the rip currents and for waves crashing violently on the beach, instead of breaking farther from shore and more calmly lapping on the sand.
But some suspect another factor: So-called beach "replenishment" or "nourishment" was performed last year, using sand from sandbars to widen and steepen eroded beaches. Barrier islands like Ocean City naturally erode and shift, but because they have been developed as if they were permanent land forms, the Army Corps of Engineers pumps sand onto the beaches about once every four years to protect buildings and property.
There's little consensus on the correlation, but some scientists argue that without sandbars, waves maintain their energy all the way to the beach, and then create rip currents when all of that water flows back out to sea.
Orrin Pilkey, professor emeritus of geology at Duke University and founder of its Program for the Study of Developed Shorelines, has long argued against development on barrier islands like Ocean City and beach nourishment projects, saying they disrupt natural cycles, killing beach ecosystems and creating more dangerous surf, including rip currents.
The correlation between beach nourishment projects and surf injuries is "well established," said Stephen P. Leatherman, a coastal scientist and professor at Florida International University in Miami.
Leatherman, who has gained celebrity as "Dr. Beach" by publishing ratings of beaches, said he was familiar with Maryland's Atlantic shore, having spent 14 years doing coastal research at College Park before heading to Florida.
Typically, he said, beach nourishment is done by pumping sand from offshore; that sand tends to be coarser than what he called the "native" sand nearer to shore. The coarser sand is heavier and more stable, he said, so it's less likely to be washed away, but it also tends to make the beach steeper.
"When the beach is steeper, it means that when the waves break, they break more dramatically. They pick you up and throw you headfirst on the beach."
Ocean City officials, including Meehan, discount such opinions.
Arbin and city engineer Terry McGean said that, if anything, pumping the sandbars onto shore should discourage rip currents. They typically form when too much water fills the trough between the beach and sandbar, breaking through the sandbar and flowing back away from shore.
Whatever was behind the rough surf, Ocean City is expecting calmer seas this summer.
A year of waves and storms has returned the beach and sandbars to a more natural profile, said Lee Gerachis, owner of Malibu's Surf Shop.
"We've had decent waves," he said. "It's not as treacherous as it was last year."
The forecast for tropical cyclones also looks favorable, though the storms are notoriously unpredictable. Climate forecasters are predicting a quiet hurricane season because conditions related to El Nino, which began in February, tend to inhibit cyclone formation.
But AccuWeather.com meteorologists said the U.S. coastline still could be vulnerable because, even though waters in the central Atlantic are relatively cool and the air on the dry side, the warmth and moisture needed to fuel storms are still present in the Gulf of Mexico. The National Hurricane Center is quick to emphasize it only takes a single storm to bring damage and flooding.
The timing of tidal cycles also contributed to last summer's heavy surf, with some "extraordinary" high tides coming during peak hours for beachgoers and coinciding with storms to make conditions worse, said Tom Perry, chief of the North Bethany Beach Patrol in Delaware. That brought waves 20 to 30 yards farther up the beach than normal.
The combination of factors makes it impossible to say what the summer will hold for beachgoers' safety in Ocean City. But the Beach Patrol is hoping for a quieter season than last year.
"We're starting out with a really nice beach," Arbin said. "I don't see the patterns that look like this summer is going to be any worse than other summers."
An earlier version of this article incorrectly identified Ocean City engineer Terry McGean. The Sun regrets the error.
Baltimore Sun reporter Timothy B. Wheeler contributed to this article.