Cuba is being battered by tropical Storm Eta bringing high winds and heavy rain.
It is expected to cause a dangerous storm surge and flash floods in the country.
Eta has already passed through parts of Guatemala where 150 people are dead or missing.
It is expected to head over southern Florida where a hurricane watch and tropical storm warning are currently in place.
The US National Hurricane Center (NHC) said the storm was passing over Cuba with sustained winds of 65mph (100km/h).
It warned that "significant, life-threatening flash and river flooding will be possible in Cuba".
A dangerous storm surge will raise levels by as much as two to four feet above normal tide levels along the coast of Cuba, the NHC said.
Cuban President Miguel Díaz-Canel tweeted on Saturday that "in the face of Eta, there is no time to waste and protection is the priority".
Storm Eta made landfall in Nicaragua on Tuesday as a Category Four hurricane with winds of 140mph and torrential rains. It then weakened into a tropical depression as it moved into neighbouring Honduras and later Guatemala.
It has since gained strength, turning into a tropical storm again.
Guatemalan President Alejandro Giammattei said around 100 people were feared dead in Quejá in the central region of Alta Verapaz alone. Some of the houses in Quejá are under 15m (50ft) of mud.
He said that rescue efforts were limited by the country having only one helicopter adequate for these operations.
Panama has reported 17 deaths and 68 people are missing, Security Minister Juan Pino said.
In Mexico, officials in the southern state of Chiapas said the storm had claimed at least 20 lives.