The National Hurricane Center (NHC) in the US has warned that Tropical Storm Isaac is likely to develop into a category two hurricane after it passes over the Florida Keys.
A storm becomes a hurricane when sustained winds reach a minimum of 74 miles per hour.
The NHC said Isaac will strengthen to hurricane status with "extremely dangerous" sustained winds of 105 miles per hour towards the middle of next week.
A dusk-to-dawn curfew is in force in New Orleans tonight after Hurricane Isaac brought flooding and stranded dozens of people.
With mean winds of 80mph and higher gusts, flooding is the biggest threat as Hurricane Isaac pushes up through Louisiana.
New Orleans has been left with localised flooding and 70% of people are without power as Hurricane Isaac passes up Louisiana.