Heavy rains have flooded parts of Haiti, killing at least 25 people, as Tropical Storm Hanna moves over the Bahamas and heads for the US coast.
A new tropical storm, Josephine, has now formed off Africa behind Tropical Storm Ike.
Both are moving westward just as Hurricane Gustav dissipates after hitting the US Gulf Coast near New Orleans.
The flurry of Atlantic storms has underscored predictions for a busier than normal hurricane season and is worrisome news for millions of people living in the Caribbean and US oil and natural gas producers in the Gulf of Mexico.
It is forecast that 14 to 18 tropical storms will form during the six-month season that began on 1 June, more than the historical average of 10.
Josephine is already the 10th, forming before the upcoming statistical peak of the season on 10 September.
By last night, Hanna was bearing down on Great Inagua Island with 100km/h winds.
However it is expected to strengthen back into a Category 1 by tonight or tomorrow, with winds of at least 119km/h.
Hanna dumped torrential rains on the southeastern Bahamas, the Turks and Caicos islands, Haiti and the Dominican Republic.
In Haiti, heavy rains caused severe flooding in the northern port city of Gonaives, where thousands of people died four years ago during a similar catastrophe.
'The city is flooded and there are parts where the water gets to 2m,' said civil protection director Alta Jean-Baptiste. 'A lot of people have been climbing onto the tops of their houses since last night to escape the flooding.'
Authorities say flooding and mudslides from the storm killed at least 25 people across Haiti, including 12 in low-lying Gonaives and three in the nearby town of Gros Morne.
Meanwhile, Ike remains around 1,500km east-northeast of the Leeward Islands and moving west at 28km/h - it is expected to reach hurricane strength this evening.
Josephine swirls over the far eastern Atlantic about 290km west-southwest of the Cape Verde Islands.
