Florida, Georgia and the Carolinas are under states of emergency as residents prepare for a possible threat from Irma.
"Irma is only one of five known hurricanes during the satellite era to have reached sustained winds of 185 mph or higher," said AccuWeather Hurricane Expert Dan Kottlowski.
Some potentially threatened areas in the Carolinas and coastal Georgia haven't been directly impacted by a major hurricane in more than 100 years, according to the Associated Press.
On Wednesday, a mandatory evacuation was issued for visitors to the Florida Keys and commercial air traffic was suspended at Key West International Airport. Evacuation orders have also been issued in parts of Miami.
The National Hurricane Center issued a hurricane and storm surge watch for parts of South Florida and the Florida Keys on Thursday.
Meanwhile, Florida Gov. Rick Scott has suspended tolls across the state's highways to help expedite the evacuation and supply-gathering process for residents.
The islands of Saint Barthelemy, Saint Martin and Anguilla in the northern Leeward Islands took a direct hit from Irma on Wednesday morning. Irma's 150 mph-plus winds and at least 12-foot storm surge caused catastrophic damage.
So far, Irma has killed at least 10 people in the Caribbean, the AP reported.
Click here to see previous reports of how Florida is preparing for Irma.
2:55 p.m. EDT Thursday: Officials have extended mandatory evacuation orders to all coastal areas, barrier islands and mobile homes in Miami-Dade County, according to the Associated Press. An interactive map showing the different zones across the county can be found here.
With the addition of the new evacuation orders, roughly 650,000 people are being told to leave their homes. This is nearly 25 percent of the population of Miami-Dade county.
Evacuation order in effect for Zones A, B and parts of C. Visit https://t.co/dqaqdgaXtF for additional information. pic.twitter.com/pL7B12OKuA
— Carlos A. Gimenez (@MayorGimenez) September 7, 2017
1:06 p.m. EDT Thursday: Georgia Gov. Nathan Deal has issued mandatory evacuation orders for Chatham County, which includes Savannah.
"Beginning Saturday, a mandatory evacuation order will take effect for Chatham County, all areas east of I-95 and some areas west of I-95 that could be impacted by this catastrophic hurricane and storm surge," Deal said.
BREAKING: Georgia governor has issued mandatory evacuation order for city of Savannah, other coastal areas, starting Saturday.
— The Associated Press (@AP) September 7, 2017
The a total of 30 counties are currently under a state of emergency in Georgia.
12:21 p.m. EDT Thursday: Cruise lines continue to cancel or change itineraries due to the approach of the deadly Category 5 Hurricane Irma, which has already devastated islands in the Caribbean.
Thirty-one sailings from cruise lines including Norwegian, Royal Caribbean and Celebrity Cruises have been impacted as of Thursday, according to Cruise Critic. So far, 13 of the affected sailings have been canceled.
One of Royal Caribbean’s ships, the 1,000-foot Enchantment of the Seas, will be used to carry the cruise line's employees and their family members away from Miami to calmer seas on Friday before Irma arrives, CNN reported.
11:29 a.m. EDT Thursday: Florida Gov. Rick Scott tweeted that fuel trucks across the state are being escorted by law enforcement officers to gas stations low on fuel.
Scott said officials are "working aggressively" around the clock to refuel the state's gas stations.
"For gas stations in evacuation zones: we need you to stay open as long as possible so people can get out," Scott said in a statement.
Florida Highway Patrol is providing escorts to fuel trucks across FL to ensure supplies are quickly refilled. pic.twitter.com/X4J2aS0PgU
— Rick Scott (@FLGovScott) September 7, 2017
Fuel truck delivering fuel to a gas station at 55th Street in Marathon this morning. Fuel also available at 63rd St. Dions. pic.twitter.com/cLzButy1Rc
— Florida Keys Sheriff (@mcsonews) September 7, 2017
Scott announced on Thursday that 3,000 additional members of the Florida Army and Air National Guard will be activated on Friday in preparation for Irma.
"These men and women are putting themselves in harm’s way to save the lives of their fellow Floridians while many of their own families are evacuating," Scott said. "I am proud of their commitment to keeping our families safe."
By Friday, all 7,000 members of the National Guard are expected to be deployed.
11:02 a.m. EDT Thursday: A hurricane watch has been issued for South Florida. This includes areas south of the Jupiter Inlet, which is on the eastern coast of the state, to Bonita Beach on the western coast and down to the Florida Keys, according to BNO News.
#BREAKING: South Florida is under a Hurricane Watch and Storm Surge Watch.#hurricanirma https://t.co/4Bk1qOn0UU#SetzerSays
— CBS4 Miami (@CBSMiami) September 7, 2017
Hurricane & Storm Surge Watches are in effect for portions of south Florida & the Florida Keys. #Irma https://t.co/h5yQYOQIjM
— NWS (@NWS) September 7, 2017