Hurricane Milton is rapidly intensifying.

On Sunday, forecasters upgraded Milton from a tropical storm to a hurricane a day earlier than anticipated. Hours later, Milton — which was projected to make landfall in Florida with Category 3 strength — is now expected to strengthen to a "major" Category 4 storm within the next two days.

The hurricane was churning in the Gulf of Mexico — about 780 miles away from Tampa — with sustained winds of 85 miles per hour, as of Sunday 8 p.m. ET.

Milton is forecast to make landfall Wednesday on the west coast of the Florida peninsula, anywhere from north of Tampa to south of Fort Myers on Florida's Gulf Coast. By then, it is anticipated to grow into a Category 4 storm with sustained winds of 145 miles per hour, according to the National Hurricane Center.

The center's director Michael Brennan urged Florida residents to complete storm preparations and seek safety by Tuesday in order to shelter in place on Wednesday. Milton is expected to exit into the Atlantic Ocean by Thursday.

All of the areas where Milton is set to strike were already hammered by Category 4 Hurricane Helene's storm surge and flooding less than two weeks ago. Milton is expected to produce similar life-threatening storm conditions, including storm surge and strong winds.

Emergency managers in several coastal counties and cities on Florida’s Gulf Coast have ordered mandatory evacuations beginning tomorrow ahead of Hurricane Milton.

Many of these orders are for people living in low-lying areas or in mobile homes. Fort Myers Beach — which was walloped by Hurricane Ian in 2022 and Hurricane Irma in 2017 — has ordered the entire island to evacuate by Monday 3 p.m. ET.

Farther up the coast, parts of Manatee, Pasco, Pinellas and Hillsborough Counties have told residents in low-lying and flood-prone areas they must leave.

In a press conference on Sunday, Florida Emergency Management Director Kevin Guthrie said the state may see its largest evacuation since Hurricane Irma in 2017, when nearly 6.8 million Floridians evacuated their homes.

Gov. Ron DeSantis on Sunday expanded the state of emergency order to include 51 out of the state's 67 counties, including all of central Florida, in preparation for Milton’s arrival. The governor’s order activates the Florida National Guard as needed and expedites debris cleanup from Hurricane Helene.

The FDOT and contractor clean-up crews continue to work days and nights to clean up from #HurricaneHelene and prepare for TS Milton. Early this morning, approximately 150 dump trucks and 45 other contracted vehicles left Tropicana Field to continue assisting in clearing debris. pic.twitter.com/rxnQFBo3WG

Meanwhile, a flood watch has already been issued for wide swaths of central and south Florida, including cities Palm Beach, Miami, Orlando and Tampa. The flood watch is in effect until Thursday.

The government of Mexico on Sunday also issued a hurricane watch for the north coast of the Yucatán peninsula from Celestún to Cabo Catoche, where a storm surge of up to 4 feet is expected.

The abnormally warm waters of the Gulf of Mexico, fueled by human-caused climate change, have turbocharged the rapid intensification of storms in recent years which are windier and rainier than past hurricanes.

As always, storms are fickle and don’t always perform as forecast. They are subject to the vagaries of atmospheric changes that can lead to wobbles, changes in their tracks, and unexpected intensifications or weakening.

With Milton reaching hurricane strength, it’s the first time there have been three simultaneous hurricanes recorded in the Atlantic Ocean after September (Kirk, Leslie and Milton) according to storm researcher Philip Klotzbach. This is the ninth hurricane to form in the 2024 season and the fifth since Sept. 25 — shattering the old record of two during that period.

Helene's death toll has surpassed 200, as Florida, Georgia, North Carolina, South Carolina, Tennessee and Virginia continue to uncover the full extent of the storm's damage.

In Florida, at least 19 people have died as a result of Helene, according to USA Today. Helene is considered one of the deadliest hurricanes to have hit the continental U.S. since Hurricane Katrina in 2005.

NPR's Chandelis Duster contributed to this report.