Florida governor Ron DeSantis has declared a state of emergency as Hurrican Dorian nears the US mainland.
Puerto Rico's Director of Public Safety Elmer Roman also warned residents to keep their guard up as the hurricane's path veers.
The hurricane will likely hit the Carribean island today, It is expected to strengthen into a category 3 storm by the time it hits Florida.
Follow live updates on the storm below
Hello and welcome to our live coverage of Storm Dorian. We'll be bringing you the latest updates on the storm as it approaches Puerto Rico.
Storm Dorian is currently a tropical storm, but is expected to develop into a hurricane at it makes landfall in Puerto Rico and the Virgin Islands.
As of 1pm UK time (8am EST), Dorian was centred about 60 miles (96 kilometres) southeast of St. Croix and moving northwest near 13 mph (20 kph).
This satellite image shows Tropical Storm Dorian as it approaches Puerto Rico in the Caribbean at 11:40 UTC.
Here is a safety message from the National Hurricane Center about potential hazards from Storm Dorian:
Storm Dorian is expected to develop into a hurricane when it reaches Puerto Rico, which is still recovering from back-to-back hurricanes that killed about 3,000 people in 2017. During a televised news conference, Puerto Rico Governor Wanda Vazquez insisted: "We are better prepared than when Hurricane Maria attacked our island."
Donald Trump has taken to Twitter to attack Puerto Rico as it braces for Storm Dorian. The president has repeated false comments about disaster relief after Hurricane Maria, and has claimed he is "the best thing that's ever happened to Puerto Rico."
The storm is predicted to pass through Puerto Rico, Vieques and the US Virgin Islands later today, all of which are currently on hurricane watch. Dorian's winds could reach 100mph over the next four days, the National Hurricane Center says.
It is expected to hitting Florida's coast as a hurricane late Sunday or early Monday.
Puerto Rico may face landslides, widespread flooding and power outages later today, making this one of the country's biggest tests since Hurricane Maria in 2017.
Here is a message from Donald Trump earlier today about Storm Dorian, which includes a dig at the mayor of San Juan.
President Trump declared an emergency Tuesday night and ordered federal assistance for local authorities.
People in Yabucoa, Puerto Rico, are putting plywood over the windows of their home as they prepare for the arrival of Storm Dorian. It is expected to reach the area at 2pm local time today.
If Dorian reaches the southeast of the US over the weekend - Labor Day weekend - it is expected to have strengthened to a category 2 hurricane. At this stage it is too early to determine the exact path of the storm for Saturday and Sunday, but it is likely it will hit parts of Florida.
Florida governor Ron DeSantis said on Tuesday: "Based on the current track of Tropical Storm Dorian, all residents on the East Coast should prepare for impacts, including strong winds, heavy rain and flooding".
Here's the latest update from the National Hurricane Center:
Speaking during a press conference today, director of US National Weather Service San Juan, Robert Garcia, said that it is possible Storm Dorian "could turn into a hurricane before it reaches Puerto Rico." However, he emphasised that the forecast could keep changing. "This is not written in stone. It could change in the next minutes, hours," he said.
Here is some updated storm tracking of Dorian moving over the Virgin Islands:
Flash flood warnings have been extended to the islands of St John and St Thomas, according to the National Weather Service of San Juan.
Here's a video of Dorian now:
Dorian has officially been upgraded from tropical storm to category 1 hurricane. It is currently moving through the Virgin Islands.
Presidential candidate Elizabeth Warren has weighed on the Trump administration's handling of the approaching storm, which has seemed overconfident at best.
Earlier today, president Trump used a tweet about White House preparation to take a dig at the mayor of San Juan, leading to more skepticism that the administration is up for what could be another significant challenge in emergency action.
Per CNN, Puerto Rico Congresswoman Jenniffer Gonzalez was asked about Donald Trump's earlier insults towards the mayor of San Juan during and interview with WAPA TV. She responded:
"We don't choose our hurricanes. We don't call ourselves, we don't wake up and say, 'come over here.' God decides that, nature decides that. We are in the Caribbean, this is a route for hurricanes and storms."
In a tweet, the representative thanks Florida representative Stephanie Murphy for her support as the hurricane draws closer to both congresswomen's homes.
As heavy rainfall hits southern Puerto Rico, a flash flood warning has been in issued.
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