BILOXI, Miss. — Hurricane Sally continued to gather strength as it meandered off the Gulf Coast, an oaf of a storm that could linger with hard rain and 100-mph winds threatening to shove massive amounts of storm water onto the shores of Mississippi, Alabama and Louisiana.

“We do anticipate a lot of flooding,” Cecilia Dobbs Walton, Biloxi’s spokeswoman, said Monday. She repeated the city’s message to its population of 46,000: “Heed the warnings. Just prepare. You’ve been through this before. You’ve been through worse ... Don’t let your guard down.”

The thud of nail guns pierced the air as residents boarded up houses at the last minute or fled the low-lying coast to higher ground. “I blocked the windows off and hope for the best,” said Tyrone Adams, a part-time courier whose 57th birthday is two days after Sally is expected to make landfall Tuesday. “I can’t stop it. Hope that we don’t get pounded on.”

In yet another sign of a dangerous and troubling time, Sally is one of at least five tropical systems that swirled across the Atlantic on Monday, the most since 1971, when there were six. In an era of human-caused climate change and warming waters, September has set a record for the most named storms to date in the Atlantic, said Colorado State tropical weather researcher Phil Klotzbach.

The season has seen a record year for tropical activity in the Atlantic, with 20 named storms forming and obliterating the typical average of 11.

The number of storms with a closed, low-pressure center this hurricane season has already nearly exhausted the alphabet to name them. Tropical storms Teddy and Vicky are the latest in a season that doesn’t end until November.

Even more storms are possible this week, as disturbances move off the coast of Africa and take advantage of ocean temperatures that are warmer than average. After the next storm, forecasters will be forced to dip into the Greek alphabet for names, which would be the earliest this rare occurrence has happened. Greek names were most recently used in the Atlantic during the 2005 hurricane season, the busiest on record.

Tropical Storm Zeta, the sixth in the Greek alphabet, closed out that season.

Climate change is causing waters in the Atlantic and Gulf of Mexico to warm, allowing storms to get stronger and more fierce. The warmer the water, the more active the hurricane season.

In addition, a La Niña weather condition that’s currently cooling waters in the Pacific Ocean creates more tropical waters in the Atlantic, a condition ripe for hurricanes.

Hurricanes Sally and Paulette are the only two that pose imminent threats to land, with Sally nearing the Gulf Coast and Paulette having moved over Bermuda overnight, bringing a wind gust of 117 mph at an elevated marine observatory.

Sally is expected to strike the Mississippi coast Tuesday morning as a category 2 hurricane. With its slow forward speed, the National Hurricane Center expects the storm to be a lingering unwelcome guest, producing heavy rains that could deluge parts of the Gulf Coast with more than two feet of rain.

This would cause widespread flooding.

If torrential downpours continue for hours in New Orleans, the capacity of the city’s pumping system would be greatly challenged. Mobile Bay in Alabama is under a storm surge warning, as the National Hurricane Center anticipates 5 to 8 feet of inundation if storm surge coincides with Tuesday evening’s high tide. Nearby Dauphin Island could experience a 6- to 9-foot surge. Alabama Gov. Kay Ivey (R) closed the beaches Monday and recommended the evacuation of flood-prone areas south of Interstate 10.

In Biloxi, nine casinos and Keesler Air Force Base intensified preparations as the storm approached. A state of emergency order sent operators of marinas and RV parks scurrying to high ground. Officials urged residents in flood-prone areas to seek shelter.

They were reminded to beware of another deadly threat: the coronavirus pandemic. Officials warned evacuees to take extra precautions to prevent spreading the virus. As the warnings blared, seawater crept closer to the strip of casinos on Highway 90 as residents and visitors packed up their campers, hitched their boats to pickup trucks and boarded up windows. City officials cleared drains and prepared rescue gear in anticipation of heavy rains and storm surges.

Dobbs Walton said the area suffered severe damage in Hurricane Nate in 2017, and over a dozen years earlier during Hurricane Katrina.

Adams claimed that his family has lost 17 houses since Hurricane Camille in 1969, but they stayed because Biloxi is their home. Crawfish boils, oyster shuckings and fun on the balmy, palm-tree dotted coast fill his memories. “I’m born and raised here. I don’t want to leave,” he said.

On Monday, the flashing party lights of a string of casinos lit the Highway 90 waterfront strip. A marquee dangled the possibility of a $250,000 jackpot and a facsimile of a giant guitar on the side of the Hard Rock Hotel and Casino Biloxi. But there was hardly anyone around to take advantage.

Parking garages were empty. MGM Park, a minor league baseball field tucked into the waterfront district, sat vacant as the skies turned gray, winds gusted and the outer bands of the storm whipped.

But Bernie and Mary Donlin were not afraid. Even with the memories of a family home destroyed in Camille and again during Katrina in 2005, they headed into the Boomtown Casino for lunch and to play the slots. They didn’t turn around until a voice on the intercom announced that Boomtown was closing early.

“If we made it through Katrina and Camille, this will just be a pain in the behind,” Bernie, 71, said as the parking lot behind him emptied out.

“I’m not worried,” Mary, 77, added.

Her husband winked. “She knows she’s got me to take care of her,” and holding hands, they headed home.