A tropical storm forming over the Turks and Caicos Islands could develop into Hurricane Cristobal, and may hit the Florida coast.
The National Hurricane Center in Miami, Florida, has issued a public advisory due to the presence of Tropical Depression 4, which is likely to become the third Atlantic storm of 2014: Hurricane Cristobal.
Cristobal could become a category-one hurricane, with 75mph (120 kph) winds within three days.
On Monday, a system path tracking close to Florida could mean a greater chance of thunderstorms, the strongest of them carrying gusty winds, the weather service said.
"It's something that every person in Florida is going to have to keep an eye for the next couple of days," said Will Ulrich, a meteorologist with the National Weather Service in Melbourne, Florida.
The National Hurricane Center's forecast shows the system moving northward in the Atlantic Ocean, with the centre passing about 200 miles east of Daytona Beach on Wednesday, Ulrich said.
However, he warned that forecasters say there's still "a considerable amount of uncertainty. There could be subtle shifts to the west or to the east."
High temperatures are expected to continue through the weekend. The high on Saturday — 97 degrees Fahrenheit — broke a record set in 1988, Ulrich said.
In the Dominican Republic, around 790 people left their homes after at least 158 homes were flooded, according to the National Centre for Emergency Operations.
Communication was severed with at least 10 communities by flooded roads and damaged bridges.
Flash flood and mudslide warnings were in place in 17 of the country's 31 provinces.
A major hurricane is considered to be category three or above, with winds hitting at least 111 mph (178 kph).
This year, two hurricanes – Arthur and Bertha – have developed in the Atlantic.
Only Arthur, a category two storm, made landfall, on North Carolina's Outer Banks in early July.