ATLANTA (REUTERS) - Hurricane Ida barrelled into Cuba on Friday (Aug 27) and churned towards a weekend US landfall along the Louisiana coast, prompting advance evacuations of New Orleans residents and oil rig workers as President Joe Biden issued a federal emergency declaration.

By midday, Ida was packing maximum sustained winds of 120kmh, according the National Hurricane Centre, which expected the storm to strengthen further before coming ashore as a major hurricane in southeastern Louisiana on Sunday.

Forecasters said Ida would likely make US landfall as a Category 3 storm on the five-step Saffir-Simpson scale with sustained winds of at least 170kmh and heavy rainfall.

Inundation from Ida's storm surge - high surf driven by the hurricane's winds - will likely reach between 10 and 15 feet around the mouth of the Mississippi River, with lower levels extending east along the adjacent coastlines of Mississippi and Alabama, according to the National Hurricane Center.

Scattered tornadoes, widespread power outages and inland flooding from torrential rain across the region were also expected.

Louisiana Governor John Bel Edwards, his state already reeling from a public health crisis stemming from a fourth wave of the Covid-19 pandemic, urged residents to ready themselves for the hurricane immediately.

"Now is the time to finish your preparations," he told a Friday afternoon news conference. "By nightfall tomorrow night, you need to be where you intend to ride out the storm."

New Orleans city officials ordered residents to evacuate areas outside the city's levee system, with voluntary evacuation notices for the rest of the parish.

Baton Rouge Mayor Sharon Weston Broome signed an emergency disaster declaration and said the city had pre-positioned sand and sandbags at eight strategic locations as part of storm preparations.

Louisiana Governor John Bel Edwards declared a state of emergency on Thursday, and on Friday Biden issued at pre-landfall federal emergency declaration at Edwards' request.

This authorised the US Department of Homeland Security and the Federal Emergency Management Agency (Fema) to coordinate disaster relief efforts in the state.

"Unfortunately, Louisiana is forecast to get a direct, strong hit from Tropical Storm #Ida, which is compounded by our current fourth surge of Covid-19. This is an incredibly challenging time for our state," Edwards wrote on Twitter.

Edwards also said he had authorized activation of all 5,000 troops in the Louisiana National Guard for emergency deployments as needed.

US energy companies racing to complete evacuations of offshore platforms in the Gulf ahead of the storm had reduced petroleum production by nearly 60 per cent and gas output by almost half, federal regulators said.

Caribbean takes first hit

Soon after being upgraded to hurricane status, Ida smashed into Cuba's Isle of Youth, off the southwestern end of the Caribbean island nation, meteorologists said.

They said the storm was expected to keep gaining strength and speed as it churned over northwestern Caribbean into the warm waters of the Gulf of Mexico, endangering the coastlines of Louisiana, Mississippi and Alabama.

If forecasts proved accurate, Ida would end up making US landfall 16 years after the region was devastated by Hurricane Katrina.

Officials in US coastal areas preparing for the storm urged residents to move boats out of harbors and encouraged early evacuations.

Officials in Louisiana's Lafourche Parish said they would enact a voluntary evacuation, especially for people in low-lying areas, mobile homes and RVs.

"By Saturday evening, everyone should be in the location where they intend to ride out the storm," Edwards said on Thursday.

Cuba's meteorology institute said Ida would cause storm surges as far east as Havana. The governor of the Isle of Youth Adian Morera said an evacuation center was ready to receive families in the main town of Nueva Gerona, and sea vessels had already been secured along the coast.

Jamaica was flooded by heavy rains, and there were landslides after the passage of the storm. Many roads were impassable, forcing some residents to abandon their homes.

Ida, the ninth named storm and fourth hurricane of the 2021 Atlantic hurricane season, may well exceed the strength of Hurricane Laura, the last Category 4 storm to strike Louisiana, by the time it makes landfall, forecasters said. But it pales in comparison to Katrina, the monster Category 5 storm that devastated the region in August 2005, claiming more than 1,800 lives.