As Idalia approaches, the Pasco County School District, north of Tampa, said its schools will be closed on Tuesday and Wednesday.

Schools in Hillsborough County, which encompasses Tampa, will also be closed Tuesday and Wednesday.

President Joe Biden spoke with Florida Gov. Ron DeSantis Monday morning and told the governor he's approving an emergency declaration for the state, according to the White House.

"President Biden said Florida will have his full support as they prepare for Idalia and its aftermath," the White House said.

The Federal Emergency Management Agency "has pre-deployed personnel and assets, including multiple Incident Management Assistance Teams," according to the White House. "FEMA’s National Response Coordination Center has also been fully activated to support any requests for federal assistance."

-ABC News' Justin Gomez

Floridians should be prepared for at least a Category 3 hurricane, Gov. Ron DeSantis warned Monday.

"This is going to be a major impact," DeSantis said at a press briefing.

DeSantis said evacuation orders will be issued for low areas along the coast.

If "you're told to evacuate, you do not need to drive hundreds of miles. You do not need to leave the state of Florida," the governor noted. "You basically need to go to higher ground in almost every instance. You can go tens of miles to a shelter, to a hotel, to a friend's house, whatever works for you, and you'll be able to ride out the storm."

-ABC News' Hannah Demissie and Will McDuffie

Idalia may rapidly intensify on Monday night and Tuesday, strengthening to a major Category 3 hurricane by Tuesday night.

Landfall is currently forecast for Wednesday morning in Florida's Big Bend area.

Storm surge is expected to be severe. It could reach 4 to 7 feet in Tampa and up to 11 feet in the Big Bend area.

Up to 10 inches of rain is possible in north Florida. Tampa Bay could see more than 6 inches of rain.

By Wednesday evening, Idalia will be weaker -- a tropical storm -- as it moves near the Carolinas with heavy rain and gusty winds. Idalia is not expected to impact the Northeast.

-ABC News' Max Golembo

There were at least three reported tornadoes on Wednesday after Idalia made landfall as a Category 3 hurricane in Florida and moved northeast across Georgia and the Carolinas as a tropical storm.

Two tornadoes were reported in South Carolina and one in Florida, with damage to structures and vehicles.

Wind gusts got up to 86 miles per hour in Mayo, Florida; 67 mph in Valdosta, Georgia; and 52 mph in Savannah, Georgia, according to the National Weather Service.

Meanwhile, as Idalia moved further inland, it produced some of the worst storm surge on record that flooded coastal cities from Florida to the Carolinas.

The highest storm surge -- up to 6.83 feet -- was recorded in Cedar Key, Florida. Tampa Bay, Florida, got hit with 4 to 5 feet, the highest storm surge since a 1921 hurricane. Charleston, South Carolina, saw 3.47 feet, the fifth highest storm surge on record, which flooded streets and neighborhoods, according to the National Weather Service.

A flash flood emergency was reported in Valdosta, Georgia.

The highest rainfall total -- 9.97 inches -- was recorded in Statesboro, Georgia. Hampton, South Carolina, got 9.61 inches of rain while Citrus Springs, Florida, had 9.48 inches. Rain was still coming down in North Carolina on Thursday morning and the state has recorded 6 to 10 inches so far, according to the National Weather Service.

-ABC News' Max Golembo