Hurricane Milton tracker: May be one of Florida's worst storms in 100 years

Mandatory evacuation orders have been issued in parts of counties along Florida's west coast and even Florida's east coast, including in Charlotte, Citrus, Collier, Hernando, Hillsborough, Lee, Levy, Manatee, Pasco, Pinellas and Volusia.

"If you live in a storm surge evacuation zone and you're asked to leave by your local officials, please do that," Michael Brennan, the director of NOAA's national hurricane center, told ABC News Live on Sunday. "You don't have to drive hundreds of miles to get to a safe place, often just tens of miles to get inland, out of that evacuation zone, to a shelter, a friend or loved one's home."

Brennan also urged Floridians to prepare a disaster kit with several days’ worth of nonperishable food, water, medicine and batteries.

Nearly 700 flights have been canceled across the country on Tuesday and another 1,500 flights are canceled on Wednesday as Hurricane Milton closes in on Florida.

The St. Pete-Clearwater International Airport, Tampa International Airport, Orlando International Airport and Sarasota Bradenton International Airport are all set to close.

The Florida Division of Emergency Services said it has partnered with Uber to provide free rides to and from shelters as residents evacuate ahead of Milton.

Hurricane Milton's maximum sustained winds were at about 155 mph early Tuesday, classifying the storm as a "powerful" Category 4 hurricane, the National Hurricane Center said.

"While fluctuations in intensity are expected, Milton is forecast to remain an extremely dangerous hurricane through landfall in Florida," the center said in a 1 a.m. ET update.

-ABC News' Jessica Gorman

As of its 11 p.m. ET update, the National Hurricane Center said that Hurricane Milton now has wind speeds of 165 mph, slowing down by 15 mph from earlier Monday.

The storm still poses an "extremely serious threat" to Florida, the NHC said.

It's currently moving toward the Northern coast of the Yucatan Peninsula, per the NHC.

It is still forecast by the NHC to weaken to a Category 3 before making landfall late Wednesday night or early Thursday morning.

-ABC News Senior Meteorologist Melissa Griffin