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People in the US state of Louisiana have been warned to prepare for the arrival of a hurricane.

Tropical Storm Francine formed in the Gulf of Mexico with sustained winds estimated at 90mph (150km/h).

Forecasters at the are expecting the storm to intensify as it drifts north-eastwards, fuelled by very warm waters - with sea surface temperatures of more than 30C (86F).

Francine is predicted to be a high end category one or category two hurricane as it makes landfall on Wednesday. Mandatory evacuations have been ordered in parts of Louisiana and a number of schools in the state have announced they will close.

A hurricane warning has been issued for the coast of Louisiana, with the risk that sustained winds could reach close to 100mph (160km/h) before Francine moves onshore.

Low-lying coastal areas could be inundated by a storm surge of up to 10ft (3m).

Rain is expected to be another feature of the storm, with 4-8in (100-200mm) forecast in large parts of Louisiana and Mississippi. The very wettest places could see up to 12in (300mm) of rain, bringing the risk of significant flash flooding.

Tropical storm warnings also cover some coastal parts of Texas, as well as north-east Mexico.

This area is no stranger to hurricanes. Hurricane Ida made landfall in 2021 as the fifth most powerful storm on record to hit the US mainland, while Hurricane Katrina - which made landfall as a powerful category three storm - killed 1,800 people back in 2005.

More recently, Hurricane Beryl brought damaging winds, flooding and power cuts to parts of Texas and Louisiana, leading to a number of deaths.

The Atlantic hurricane season runs from June until November - with early September typically representing the peak of storm activity.

But despite forecasts of an "extremely active" hurricane season the last few weeks have brought the longest lull in storm activity in more than 50 years, with no storms developing since mid-August.

Scientists at have suggested a number of reasons for this.

One key factor is unusual weather patterns across Africa that have brought rain to parts of the Sahara that rarely see wet weather.

It means the thunderstorms that normally fuel Atlantic hurricanes have been further north than usual, in areas where strong winds high in the atmosphere can tear developing storms apart.

The delayed arrival of La Niña and large amounts of Saharan dust in the atmosphere may also have played a part.

But an an above average season overall is still predicted with activity expected to increase in the coming weeks.