Tropical Storm Erika hit the island of Dominica, in the eastern Caribbean, killing at least 20 people.
The storm caused floods and mudslides that have set the country back 20 years, Dominica’s PM Roosevelt Skerrit said.
Haiti and the Dominican Republic are now expecting 53mph winds.
A state of emergency has been declared in Florida, where the storm is expected on August 30.
PM Roosevelt Skerrit said in a televised address on August 28 that hundreds of homes, bridges and roads had been destroyed.
He said: “It is with heavy heart that I address you, you can well imagine the hell that it has been for me since I heard of the passing of Tropical Storm Erika and the damage it has done to our dear people and beloved country. But we all have to pull ourselves together.
“The extent of the devastation is monumental. We have, in essence, to rebuild Dominica.”
Erika dumped 15in of rain.
At least 31 people on the island of 72,000 people have been reported missing, according to officials with the Barbados-based Caribbean Disaster Emergency Response Agency.
Other Caribbean nations have issued tropical storm warnings.
In Puerto Rico, Erika knocked out power to more than 200,000 people and caused more than $16 million of damage to crops including plantain, bananas and coffee, AP reported.
The US National Hurricane Centre said the system was expected to move north across the island of Hispaniola – shared by Haiti and the Dominican Republic – where the high mountains would weaken it to a tropical depression on Saturday.
Meanwhile, Florida Governor Rick Scott declared a state of emergency as a precaution with officials urging people to prepare by stockpiling food and water and fuelling their vehicles.
Separately, in the Pacific Ocean, Hurricane Ignacio strengthened into a hurricane with maximum sustained winds of 90mph, centered south-east of Hilo in Hawaii, and moving north-west.