image sourceNational Weather Serviceimage captionThe hurricane is currently over Cuba and will hit the US by Sunday

The mayor of New Orleans has called for residents to evacuate unprotected city neighbourhoods as Hurricane Ida bears down on the Louisiana coastline.

"Now is the time," said New Orleans Mayor LaToya Cantrell in a Friday news conference, calling for those living outside the city levee system to flee.

Forecasters say that the hurricane will reach category 3 strength by the time it reaches the US on Sunday.

It is expected to bring heavy rain and winds to parts of Cuba as well.

The impact of climate change on the frequency of storms is still unclear, but we know that increased sea surface temperatures warm the air above and make more energy available to drive hurricanes, cyclones and typhoons. As a result, they are likely to be more intense with more extreme rainfall. 

In its latest bulletin, the National Hurricane Center (NHC) in Miami declared Ida to be a hurricane with current wind speeds of 75mph (125km/h).

Ida is due to pass over western Cuba on Friday, and could make landfall in the US on Sunday. Cuban weather officials have issued warnings in the Isle of Youth and other western provinces.

Coincidentally, Sunday marks the 16th anniversary of Hurricane Katrina, a category 3 hurricane which devastated New Orleans in 2005. Katrina flooded 80% of the city and killed more than 1,800 people.

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Dangerous storm surges are also forecast both in Cuba and the US. Experts say that if they hit at a time that coincides with high tides, sea water could flood over the New Orleans levee system and into the city.

The levees are a system of flood walls, built to protect low-lying New Orleans, and strengthened after the devastation of 2005.

Warm waters across the Gulf of Mexico are fuelling the storm's rapid intensification, the agency said, adding that flooding could also affect the neighbouring states of Mississippi and Alabama.

The @CityOfNOLA is issuing a mandatory evacuation for areas outside the levees (red) and a voluntary evacuation for the rest of the parish (yellow).#Ida could bring up to 11ft surge outside levees, and dangerous winds & heavy rain for the full area.

— NOLA Ready (@nolaready) August 27, 2021
The BBC is not responsible for the content of external sites.View original tweet on Twitter

"Steady to rapid strengthening is expected when Ida moves over the south-eastern and central Gulf of Mexico over the weekend, and Ida is expected to be a major hurricane when it approaches the northern Gulf coast," said the NHC bulletin issued on Friday afternoon.

Governor Bel Edwards has declared a state of emergency and called for anyone along the state's coastline to shelter in place starting on Saturday evening. The White House has said that the federal government is also making emergency aid plans.