UPDATE: 8:24 p.m. EDT — Former Florida Gov. Jeb Bush urged his fellow Floridians to take Hurricane Matthew seriously Tuesday as the storm ravaged Cuba and Haiti and seemed poised to hit the Sunshine State next.
"Florida friends, Hurricane #Matthew is serious. Get a plan, heed warnings from officials and follow @NHC_Atlantic and @FLSERT for updates," he tweeted.
UPDATE: 7:30 p.m. EDT — More than 4 million children in Haiti could be hit by Hurricane Matthew, United Nations officials said Tuesday. Many schools are being used to shelter evacuees and students have been told to stay home.
“This is the worst storm Haiti has seen in decades and the damage will no doubt be significant,” said Marc Vincent, UNICEF Representative in Haiti. “Water-borne diseases are the first threat to children in similar situations - our first priority is to make sure children have enough safe water.”
The storm was expected to pummel Haiti's southern coast, one of the island-nation's poorest and most densely populated regions.
UPDATE: 6:45 p.m. EDT — School districts across South Florida were urging parents and students to stay home this week as state officials watched to see where Hurricane Matthew would hit next. Broward, Palm Beach, Martin and Port St. Lucie county schools will be closed Thursday and Friday. Miami-Dade county officials said they were still waiting to make a decision.
UPDATE: 6:12 p.m. EDT — A bridge linking Port-au-Prince with southern Haiti collapsed Tuesday as Hurricane Matthew pounded the island nation, knocking down trees and communication towers.
"It’s the worst hurricane that I’ve seen during my life," Fidele Nicolas, a civil protection official, told The Associated Press. "It destroyed schools, roads, other structures."
UPDATE: 5:40 p.m. EDT — Hurricane Matthew hit Cuba's southeastern coast Tuesday afternoon, bringing winds near 140 mph to the impoverished island nation. Matthew is expected to remain a powerful hurricane through the week, and state officials in Florida and South Carolina urged residents to prepare for the storm to potentially hit the United States Thursday.
UPDATE: 5:01 p.m. EDT — Florida Gov. Rick Scott plans to send 500 additional National Guard members throughout the state to help residents deal with Hurricane Matthew's aftermath. He told reporters Tuesday afternoon he was considering declaring evacuation orders later in the day.
"We have to be prepared for a major hurricane," Scott said. "We have to prepare for a direct hit." He advised Floridians along the state's east coast: "If you are able to leave early, leave now."
UPDATE: 4:01 p.m. EDT — With flooding and mudslides from Hurricane Matthew still possible across Haiti, Port-au-Prince resident Karl Jean-Jeune told the Weather Network he was worried about his family members.
"Trees are downed, fences are down and winds are blowing a lot of the rain into houses," he said. "They're also talking about metal sheets that are used to cover houses, they are flying all over the place. Most windows are open and exposed, so there is debris in my grandmother's home."
Pictures of Haiti's damage from the Category 4 storm continued to dominate social media on Tuesday. If you're hoping to help storm survivors, read our article on organizations that have coordinated disaster relief funds for Hurricane Matthew.
UPDATE: 3:35 p.m. EDT — South Carolina's College of Charleston will close all of its campuses starting at 6 p.m. local time Tuesday because of Hurricane Matthew. "The College encourages all faculty, staff and students to begin evacuating as soon as possible in order to avoid possible traffic delays," the school wrote on its website.
UPDATE: 3:31 p.m. EDT — South Carolina Gov. Nikki Haley has announced that people living along the state's coast will begin evacuating Wednesday due to Hurricane Matthew. At a news conference, Haley said she wanted residents to be at least 100 miles from the shore, the Post and Courier reported.
UPDATE: 3:15 p.m. EDT — Sprint is getting rid of international call and text charges for people in Haiti, Jamaica, the Bahamas and other Caribbean countries affected by Hurricane Matthew through Friday.
"We are sending thoughts and prayers to those who may be impacted by Hurricane Matthew," CEO Marcelo Claure said in a news release. "We want to do what we can to help our customers stay connected with loved ones."
UPDATE: 3 p.m. EDT — President Barack Obama is planning to travel to the Federal Emergency Management Agency offices to look at plans for Hurricane Matthew, White House press secretary Josh Earnest tweeted Tuesday.
The National Hurricane Center said Florida could see tropical storm conditions on Thursday. Authorities in North Carolina were on high alert, too, while the University of South Carolina wrote in a statement that it was monitoring Matthew to see whether the storm would affect its weekend football game.
UPDATE: 2:33 p.m. EDT — The National Hurricane Center turned its attention to Cuba Tuesday afternoon in its 2 p.m. EDT update on Hurricane Matthew, the "extremely dangerous" Category 4 storm lashing the Caribbean. The system was about 65 miles east-southeast of Guantanamo, Cuba, and about 55 miles south-southwest of its eastern tip.
Matthew was moving at about 10 mph. It had triggered a slew of tropical storm warnings and hurricane watches in Cuba, Haiti, the Dominican Republic and Florida.
In preparation for the storm, more than 700 people were evacuated from the Naval Base at Guantanamo Bay, the United States Department of Defense wrote in a news release. They were flown to Pensacola, Florida. Meanwhile, the detainees were "safe and secure" in "solid, concrete buildings ... where they can be sheltered in place," spokesman and Navy Capt. Jeff Davis said in the release.
UPDATE: 2:11 p.m. EDT — The United States military is ready to help Haiti recover from Hurricane Matthew. The USS George Washington, USS Mesa Verde and USNS Comfort — the last one a hospital ship — were preparing to travel to the storm-torn nation, USNI News reported.
Haiti reached out and asked for the aid in the wake of the Category 4 storm, according to the Navy Times.
UPDATE: 1:15 p.m. EDT — Rivers in Haiti were rising and, in some cases, flooding Tuesday as Hurricane Matthew moved toward Cuba. "The river has overflowed all around us," pastor Louis St. Germain told CNN. "It's terrible... a total disaster."
The Category 4 storm could cause "life-threatening flash floods and mudslides" in southern and northwestern Haiti as well as parts of the Dominican Republic and Cuba, according to the National Hurricane Center.
UPDATE: 12:30 p.m. EDT — Celebrities like Patricia Arquette and Connie Britton had Haiti in their thoughts Tuesday as Hurricane Matthew wrecked Haiti. The Telegraph reported that seven people were dead, but the number had not yet been confirmed.
"It's much too early to know how bad things are, but we do know there are a lot of houses that have been destroyed or damaged in the south," Marie Alta Jean-Baptiste, of the Civil Protection Agency, told the Associated Press.
UPDATE: 12:01 p.m. EDT — Haiti, which was pummeled by Hurricane Matthew on Tuesday, is set to have a presidential election on Sunday. Though electoral council president Léopold Berlanger told advisers to suspend their campaign-related activities due to the Category 4 storm, he didn't call off the election itself, according to Haiti Libre.
At least one candidate was using the inclement weather as an opportunity to connect with voters. Jude Célestin tweeted that he had sympathy for families affected by Hurricane Matthew.
In other political news, the U.S. Embassy in Haiti announced it would be closed Wednesday.
UPDATE: 11:44 a.m. EDT — Shortly after the National Hurricane Center issued an updated forecast for Hurricane Matthew showing the storm moving along the east coast of Florida, Sen. Marco Rubio, R-Fla., tweeted that residents should "take it serious."
The center put out a hurricane watch from Deerfield Beach to the county line between Volusia and Brevard. "Interests elsewhere in Hispaniola and in the Florida Peninsula and the Florida Keys should monitor the progress of Matthew," it added.
UPDATE: 11:31 a.m. EDT — Haiti's Habitat for Humanity branch tweeted Tuesday that the regions that appeared to have sustained the most damage from Hurricane Matthew were the south and west.
As photos of the weather and flooded roads continued to circulate on social media, former head of the Haitian diplomatic mission to the United Kingdom Jean Pillard warned people not to share misleading content.
UPDATE: 11:12 a.m. EDT — The latest update from the National Hurricane Center revealed the Category 4 storm Hurricane Matthew was about 35 miles from Tiburon, Haiti, on Tuesday with winds of 145 mph. The system was moving north at 10 mph toward eastern Cuba.
"Tropical storm conditions are expected to continue spreading across the remainder of Haiti today, eastern Cuba later this morning, the southeastern Bahamas later today, and the central and northwestern Bahamas Tuesday night and Wednesday, making outside preparations difficult or dangerous," the center wrote.
The center put out a tropical storm watch for parts of Florida Tuesday as Matthew battered Haiti.
UPDATE: 11:05 a.m. EDT — As the Category 4 storm Hurricane Matthew ravaged the Caribbean Tuesday, the National Hurricane Center issued an advisory for a new system nearby. Tropical Storm Nicole was located about 525 miles northeast of Puerto Rico and was moving northwest at about 8 mph. There was no threat to land yet.
UPDATE: 10:57 a.m. EDT — T-Mobile has announced free calling and texting to and from people in Hurricane Matthew-affected areas, including Haiti, Jamaica, Cuba and the Bahamas. Charges will be waived from Tuesday through Friday, according to a news release.
"Our thoughts and prayers are with everyone in the path of this powerful storm," CEO John Legere said in the release. "Please be sure to check on your loved ones."
UPDATE: 10:43 a.m. EDT — Hurricane Matthew became the first Category 4 storm to make landfall in Haiti in more than five decades on Tuesday, according to the National Hurricane Center. Hurricane Cleo wrecked the country in late August 1964 and killed nearly 200 people, Weather Underground reported.
On Tuesday, people in Haiti were posting social media photos of floods, damage and devastating rains:
UPDATE: 10:17 a.m. EDT — The Weather Channel wrote Tuesday that Hurricane Matthew is "increasingly likely to have significant impacts along the Southeast U.S. coast later this week." Florida was getting ready for the possibility that the Category 4 storm could slam the peninsula, with counties even in the center of the state offering residents free sandbags, the Orlando Sentinel reported.
"If Hurricane Matthew directly impacts Florida, there could be massive destruction which we haven’t seen since Hurricane Andrew devastated Miami-Dade County in 1992," Gov. Rick Scott said in a Monday news release. "That is why we cannot delay and must prepare for direct impact now."
UPDATE: 9:50 a.m. EDT — More than 1,000 people were in shelters Tuesday as Hurricane Matthew hit Haiti, the Associated Press reported. So far, one person had died and another was missing.
"Everyone is trying to find a safe place to protect themselves," Tiburon mayor Remiza Denize told Reuters. "The situation is very difficult."
The Category 4 storm inspired hurricane warnings for Haiti; the Cuban provinces of Guantanamo, Santiago de Cuba, Holguin, Granma and Las Tunas; and much of the Bahamas. Jamaica and parts of the Dominican Republic were under a tropical storm warning Tuesday.
You can watch local news channels' coverage of Hurricane Matthew here. The next update from the National Hurricane Center is expected to drop at 11 a.m. EDT.
UPDATE: 9:28 a.m. EDT — The interim president of Haiti, Jocelerme Privert, told reporters Tuesday that the nation was already struggling with Hurricane Matthew, a Category 4 storm that recently made landfall.
"We've already seen deaths," BBC News reported he said. "People who were out at sea. There are people who are missing. They are people who didn't respect the alerts. They've lost their lives."
Haiti, a poor country still recovering from a variety of recent natural disasters, could take a serious hit from Matthew. The storm could cause surge up to 10 feet and swells "likely to cause life-threatening surf and rip current conditions," according to the National Hurricane Center.
While the United States' political system prepares for the possibility of an October surprise, the Atlantic Ocean is dealing with one of its own. Hurricane Matthew, a Category 4 storm, made landfall in Haiti early Tuesday, causing widespread warnings and worrying Floridians tracking the forecast of the "extremely dangerous" system.
As of 8 a.m. EDT, the National Hurricane Center announced that Hurricane Matthew's eye was about 10 miles east of Tiburon, Haiti, and about 125 miles south of Cuba. It had maximum sustained winds of 145 mph and was moving at about 9 mph.
"Some fluctuations in intensity are possible during the next couple of days, but Matthew is expected to remain a powerful hurricane through at least Wednesday night," the center wrote. "Life-threatening flash floods and mudslides are likely from this rainfall in southern and northwestern Haiti, the southwestern Dominican Republic and eastern Cuba."
Haitians were already seeing damage from the storm, which had killed at least one man already Tuesday morning, Reuters reported. Hundreds of people had been evacuated from their homes as forecasters warned the country could see more than three feet of rain.
"We’re expecting a lot of houses to go down because of the poor housing infrastructure in a lot of the rural areas where we work," aid worker John Hasse told USA Today. "With wind this strong, it will be extremely damaging and dangerous and homes for the average person are made of mud and sticks or poorly constructed cinderblocks."
Americans were keeping an eye on Matthew as well Tuesday morning. The hurricane center recommended people in the Sunshine State, especially the Keys, monitor the storm's progress. The current path has the storm skirting the east coast of Florida.
Gov. Rick Scott declared a state of emergency in all Florida counties on Monday. NBC News meteorologist Bill Karins said Matthew could still be a Category 3 storm when it gets to Florida. He added that the "possibility exists for mandatory evacuations."
Matthew is the 13th named storm in the Atlantic hurricane season, which ends Nov. 1.
This is a breaking news story. Check back for updates.