TALLAHASSEE, Fla. — An enormous Hurricane Helene swamped parts of Mexico on Wednesday as it churned on a path forecasters said would take it to Florida as a major storm with a surge that could swallow entire homes, a chilling warning that sent residents scrambling for higher ground, closed schools, and led to states of emergency throughout the Southeast.

The storm’s center was about 110 miles northeast of Cozumel, Mexico, on Wednesday, the U.S. National Hurricane Center said, and Helene was expected to intensify and grow as it crosses the Gulf of Mexico.

The hurricane ranks in the 90th percentile for its sheer size, and it could create a surge as high as 18 feet in places, forecasters said. The fast-moving storm’s wind and rain could penetrate far inland, even as it weakens after landfall in Florida late Thursday, authorities warned.

Helene became a hurricane Wednesday morning and was moving at nearly 10 mph with top sustained winds of 80 mph later in the afternoon, but it was expected to intensify over the warm, deep waters of the Gulf. Forecasters said it should become a major Category 3 or higher hurricane Thursday with winds above 110 mph. Its center is projected to hit Florida’s Big Bend area, the curving stretch of Gulf coastline in the state’s north.

In Tallahassee, where stations had started to run out of gas, 19-year-old Florida A&M student Kameron Benjamin filled sandbags with his roommate to protect their apartment before evacuating. Their school and Florida State shut down.

“This hurricane is heading straight to Tallahassee, so I really don’t know what to expect,” Benjamin said.

As Big Bend residents battened down their homes, many saw the ghost of 2018’s Hurricane Michael. That storm rapidly intensified and crashed ashore as a Category 5 that laid waste to Panama City and parts of the rural Panhandle.

“People are taking heed and hightailing it out of there for higher ground,” said Kristin Korinko, a Tallahassee resident who serves as the commodore of the Shell Point Sailboard Club, on the Gulf Coast about 30 miles south of Tallahassee.

But Robbie Berg, a national warning coordinator for the hurricane center, warned: “Please do not compare it to other storms you may have experienced over the past year or two.”

Areas 100 miles north of the Georgia-Florida line can expect hurricane conditions. Tennessee, Kentucky and Indiana could get rainfall. Landslides were possible in southern Appalachia, with catastrophic flooding predicted in the Carolinas and Georgia.

Parts of Mexico’s Yucatan Peninsula were under hurricane warnings as Helene wound between it and the western tip of Cuba and into the Gulf of Mexico. The storm formed Tuesday in the Caribbean, and it flooded streets and toppled trees as it passed offshore and brushed the resort city of Cancun.

In Cuba, authorities moved cattle to higher ground and medical brigades went to communities often cut off by storms. The government preventively shut off power in some communities as waves as high as 16 feet slammed Cortes Bay. In the Cayman Islands, schools remained closed as flood warnings continued and residents pumped water from flooded homes.

Wind-driven waves battered Florida’s Key West on Wednesday. Tropical storm warnings were in effect for the upper Keys, southern Florida and the state’s northeast coast and were extended northward Wednesday morning to Altamaha Sound, Ga. A tropical storm watch was in effect for the South Carolina coast north of the South Santee River to Little River Inlet.