Helene strengthened into a hurricane on Wednesday as forecasters warned it could become a major Category 3 or 4 storm before it makes landfall along Florida's Gulf Coast late Thursday.

The storm is expected to bring "life-threatening storm surge, damaging winds and flooding rains" to a large portion of Florida and the Southeast, the National Hurricane Center warned.

The governors of Florida, Georgia and North Carolina declared states of emergency ahead of its arrival. Tampa International Airport announced that it will suspend operations on Thursday ahead of Helene's arrival.

Multiple counties in Florida issued mandatory evacuation orders for people in low-lying areas. Residents in the storm's potential path have been told to prepare for up to a week without electricity.

"It's a big, big storm," Florida Gov. Ron DeSantis said at a press briefing Wednesday. "Many people will lose power ... be prepared for that."

Where is the storm and what is its path?

According to the National Hurricane Center's latest advisory, Helene — with maximum sustained winds of 80 mph — is located about 110 miles north-northeast of Cozumel, Mexico, and 480 miles south-southwest of Tampa, Fla., and is moving north-northwest at 10 mph.

The storm is expected to rapidly intensify and come ashore along the Gulf Coast of Florida as a Category 3 storm, with maximum sustained winds exceeding 111 miles per hour.

"Damaging hurricane-force winds are expected along portions of the coast of the Florida Big Bend, where a Hurricane Warning is now in effect," the hurricane center said. "Preparations to protect life and property should be complete by early Thursday."

In addition to high winds, the storm will threaten millions of residents along the Gulf Coast with up to 12 inches of rainfall, as well as the possibility of tornadoes. Before it heads up into the Gulf of Mexico, Helene will bring heavy rain to portions of the western Caribbean, potentially mudslides and flooding across western Cuba. The system will also pose the threat of inland flooding across several U.S. states.

"Considerable flash and urban flooding is expected across portions of Florida, the Southeast, southern Appalachians, and the Tennessee Valley Wednesday through Friday," the National Hurricane Center said.

There is the potential for life-threatening storm surge along the entire Florida peninsula, the weather service warned.

How is Florida preparing?

DeSantis expanded a state of emergency on Tuesday to 61 counties ahead of the storm. Helene is expected to make landfall near the Big Bend region of the Florida panhandle, which was pummeled by Hurricane Debby earlier this season.

The declaration allows the state to execute its Comprehensive Emergency Management plan, allowing the use of resources for any logistical, rescue or evacuation operations.

“Now is the time to make an emergency plan, know your evacuation zone, and be as prepared as possible for the storm,” DeSantis said in a post on X.

Many cities and counties in Florida opened designated sites for residents to fill sandbags ahead of the storm.

Evacuation zones

Officials urged people in low-lying areas to consult a website outlining evacuation zones, and to heed evacuation orders. Mandatory evacuations were issued in 14 counties, including Pinellas and Hillsborough, as of midday Wednesday.

The University of Tampa, which is in one of the zones under mandatory evacuation orders in Hillsborough County, said it was working evacuate all residential buildings on its campus.

The Tampa Bay Bay Times reported that many grocery stores in the Tampa area sold out of water Tuesday as hurricane shoppers stocked up on supplies.

And Tampa International Airport announced that it will suspend operations on Thursday ahead of Helene's arrival.

Watches and warnings

As of 2 p.m. ET on Wednesday, a hurricane warning was in effect for:

Anclote River to Mexico Beach, Florida

Cabo Catoche to Tulum, Mexico

A "hurricane warning" means that hurricane conditions are expected somewhere within the warning area. It is typically issued 36 hours before the anticipated arrival of tropical-storm-force winds.

A hurricane watch was in effect for:

Pinar del Río Province, Cuba

Englewood to Anclote River, including Tampa Bay

A "hurricane watch" means hurricane conditions are possible within the watch areas. It is usually issued 48 hours before the hurricane is anticipated to hit.

A tropical storm warning was in effect for:

Dry Tortugas

All of the Florida Keys

The west coast of Florida from Flamingo to Anclote River, including Tampa Bay

West of Mexico Beach to the Okaloosa/Walton County Line

The east coast Florida from Flamingo north to South Santee River

Lake Okeechobee

Rio Lagartos to Tulum, Mexico

Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth

A "tropical storm warning" means that tropical storm conditions are expected in the warning areas within the next 36 hours.

A tropical storm watch was in effect for:

The coast of South Carolina north of South Santee River to Little River Inlet

A "tropical storm watch" means that tropical storm conditions are possible within the watch area.

A storm surge watch was in effect for:

Indian Pass, southward to Flamingo

Tampa Bay

Charlotte Harbor

A "storm surge watch" indicates the possibility of life-threatening flooding, such as rising water moving inland from the coast.

Biden approves Florida emergency declaration

President Biden approved Florida's emergency declaration on Tuesday, authorizing the Federal Emergency Management Agency (or FEMA) and U.S. Department of Homeland Security to assist state and local officials in coordinating disaster relief efforts.

In a statement, White House spokesman Jeremy Edwards said that "federal resources and personnel are prepositioned, including generators, food, and water, along with search and rescue and power restoration teams."

"FEMA has also deployed teams to Florida and Alabama to embed with local emergency response personnel to support their efforts, as needed," Edwards added. "We urge residents in the path of the storm to stay vigilant."