Hurricane Helene has rapidly strengthened in the Caribbean Sea as it moves northward between the coasts of Mexico and Cuba toward the United States, prompting authorities to declare a state of emergency in Florida.

Helene is expected to move over deep, warm water and intensify further on Wednesday as the hurricane tracks north across the Gulf of Mexico, the U.S. National Hurricane Center (NHC) said.

According to the NHC, heavy rainfall is forecast for the southeastern US starting on Wednesday, with “life-threatening storm surge” along the entire west coast of Florida.

On Wednesday afternoon, Helene was located about 135 kilometers (85 miles) from Cozumel, Mexico, and about 810 kilometers (503 miles) south-southwest of Tampa, on the west coast of Florida, as the storm moved toward the northwest at 17 km/h (10 mph) with maximum sustained winds of 130 km/h (80 mph).

High winds caused power outages in the Cayman Islands, heavy rains and waves up to 10 feet high.

Many people in Cuba are also worried about the storm. The outer bands are expected to reach the capital Havana, which is already struggling with chronic power outages.

Mexico is still reeling from Hurricane John, which tore through the Pacific coast on Monday and Tuesday, killing two people, blowing corrugated iron roofs off homes, causing mudslides and toppling trees, officials said.

John weakened to a depression after making landfall, but strengthened back into a tropical storm on Wednesday. The storm is expected to make landfall again on Thursday in the Mexican state of Guerrero, about 96 miles (155 km) north of Acapulco.

It is expected to become a ‘major’ hurricane

Helene is expected to strengthen into a major hurricane — a Category 3 or higher — on Thursday, the day it reaches Apalachee Bay on Florida’s Gulf Coast, according to the official forecast. The NHC has issued hurricane warnings for part of Mexico’s Yucatan Peninsula and Florida’s northwestern coastline, where major storm surges of up to 15 feet (4.5 meters) were expected.

“It’s going to be a very large system that will impact all of Florida,” said Larry Kelly, hurricane specialist with the NHC.

9/25 5:00 AM EDT: Life-threatening storm surge threat from tropical storm #Helene along the entire west coast of the Florida peninsula and Florida Big Bend, where a storm surge warning is in effect. Residents in those areas should follow the advice of local officials. photo.twitter.com/EorwuqPfar

— NHC Stormvloed (@NHC_Surge) September 25, 2024

Florida Governor Ron DeSantis declared a state of emergency for most counties in the state. Helene is expected to pass close to the state capital, Tallahassee. Local officials have been concerned about extensive tree damage.

Federal authorities were positioning generators, food and water, along with search and rescue teams and power restoration crews, the White House said.

The storm is expected to be unusually large and fast, meaning storm surge, wind and rain will likely extend hundreds of miles from the storm’s center, the NHC added. States as far inland as Georgia, Tennessee, Kentucky and Indiana could get rain.

Some residents along the Gulf Coast in Florida’s Panhandle have already evacuated to safer areas inland, with memories of recent storm surges still fresh in their minds.

In 2018, Hurricane Michael struck Mexico Beach, about 100 miles (160 km) west of where Helene is expected to make landfall. Michael quickly became a devastating Category 5 hurricane, taking residents by surprise, causing an estimated $25.5 billion in damages and killing 59 people.

In 2023, another Category 3 storm, Hurricane Idalia, left as many as 500,000 customers without power after the hurricane struck Florida’s northwest coast, also causing extensive water damage from storm surge. Idalia was the strongest hurricane to hit Florida’s Big Bend region since 1950.

Helene is the eighth named storm of the current Atlantic hurricane season, which runs from June 1 to November 30, and the fourth to make landfall in the U.S. Hurricane Francine struck the Louisiana Gulf Coast as a Category 2 storm just two weeks ago.

Since 2000, there have only been three other years, other than 2024, in which four or more storms made landfall on the continental U.S.

This year’s hurricane season coincides with a homeowners insurance crisis in several U.S. states, caused by rising rates and a reluctance by private insurers to provide coverage in coastal areas.

The U.S. National Oceanic and Atmospheric Administration predicted an above-average Atlantic hurricane season this year due to record-breaking warm ocean temperatures. It predicted 17 to 25 named storms, with four to seven major hurricanes of Category 3 or higher.

But the season is off to a slow start, leaving meteorologists searching for factors that may have hampered the formation of large storms as they crossed the Atlantic Ocean’s “hurricane corridor.”