Tropical storm Isaac is bringing gale-force winds and heavy rainfall to Haiti, and is due to hit the capital on Saturday afternoon, local time.
Around 400,000 people still live tent cities in Port-au-Prince, Haiti's capital, following the devastating earthquake in 2010.
The Haitian government is attempting to move people into more resilient buildings prior to the storm, but many are still living in their flimsy tent shelters.
A spokesman for the U.S. Hurricane Center in Miami, Florida, Dennis Feltgen has said that “that kind of rain is going to cause some life-threatening flash floods and mudslides”.
Forecasters are predicting as much as eight to twelve inches of rain may fall on the island of Hispaniola, shared between Haiti and the Dominican Republic.
However, the main threat seems to be aimed at Les Cayes on the southwestern coast, a city of around 45,000 people that is prone to floods during heavy rain.
The storm has already hit the Dominican Republic, with winds as strong as 95 km/h and heavy rains, causing floods and knocking down trees.
There are also tropical storm and hurricane warnings in effect for Cuba and Florida.