The approach of Tropical Storm Isaac has forced the US Republican party to delay discussions at its national convention in Tampa, Florida.
Official business will not now get underway until Tuesday.
The party is due to formally nominate Mitt Romney as its presidential candidate.
Isaac has already lashed Cuba with strong winds and rain. No deaths or injuries have been reported on the island, but the storm has left a trail of damage in its wake.
In Haiti, at least six people have been killed, including a 10-year-old girl.
There is flooding in parts of the capital Port-au-Prince and tents have been flattened in camps, where thousands of people are still living after a devastating earthquake more than two years ago.
Aid workers are worried the flood waters could re-ignite a deadly cholera epidemic.