HAVANA — Hurricane Ian tore into western Cuba as a major hurricane Tuesday and left 1 million people without electricity, then churned on a collision course with Florida over warm Gulf waters amid expectations it would strengthen into a catastrophic Category 4 storm.

Ian made landfall in Cuba’s Pinar del Rio province, where officials set up 55 shelters, evacuated 50,000 people, and took steps to protect crops in the nation’s main tobacco-growing region. The U.S. National Hurricane Center said Cuba suffered “significant wind and storm surge impacts” when the hurricane struck with top sustained winds of 125 mph.

Ian was expected to get even stronger over the warm Gulf of Mexico, reaching top winds of 130 mph approaching the southwest coast of Florida, where 2.5 million people were ordered to evacuate.

Tropical storm-force winds were expected across the southern peninsula late Tuesday, reaching hurricane-force Wednesday — when the eye was predicted to make landfall. With tropical storm-force winds extending 140 miles from Ian’s center, damage was expected across a wide area of Florida.

It was not yet clear precisely where Ian would crash ashore. Its exact track could determine how severe the storm surge is for Tampa Bay, said University of Miami hurricane researcher Brian McNoldy. Landfall south of the bay could make the impact “much less bad,” McNoldy said.

Gil Gonzalez boarded up his windows Tuesday and had sandbags ready to protect his Tampa home. He and his wife had stocked up on bottled water and packed flashlights, battery packs for their cellphones and a camp stove before evacuating.

“All the prized possessions, we’ve put them upstairs in a friend’s house and nearby, and we’ve got the car loaded,” Gonzalez said on his way out. Florida Gov. Ron DeSantis urged people to prepare for extended power outages, and to get out of the storm’s potential path.

He said about 30,000 utility workers have already been positioned around the state but it might take days before they can safely reach some of the downed power lines.

Hundreds of residents were being evacuated from several nursing homes in the Tampa area, where hospitals were also moving some patients. Airports in Tampa, St. Petersburg and Key West closed. Busch Gardens in Tampa closed ahead of the storm, while several Orlando-area theme parks, including Disney World and Sea World, planned to close today and Thursday.

Ian’s forward movement was expected to slow over the Gulf, enabling the hurricane to grow wider and stronger. The hurricane warning expanded Tuesday to cover roughly 220 miles of Florida’s west coast. The area includes Fort Myers as well as Tampa and St. Petersburg, which could get their first direct hit by a major hurricane since 1921.

Forecasters said the storm surge could reach 12 feet if it peaks at high tide. Rainfall near the area of landfall could top 18 inches.

Forecasters warned the hurricane will be felt across a large area as it plows across Florida with an anticipated turn northward.

Flash floods were possible across the whole state.