Photos: Louisiana braces for fast-approaching Hurricane Ida

New Orleans : People evacuating ahead of Hurricane Ida clogged roads headed north on Saturday from the US Gulf Coast, with the strengthening storm set to hit New Orleans 16 years to the day after devastating Hurricane Katrina.

"Ida is turning into a very, very dangerous storm," President Joe Biden said as it built to a Category 2 hurricane, packing 100 mile (160 kilometer) per hour sustained winds and heavy rain.

Traffic was heavy leaving New Orleans and other cities as officials warned locals to leave immediately or hunker down to ride out the storm.

"Ida is expected to be an extremely dangerous major hurricane when it approaches the northern Gulf coast on Sunday," the National Hurricane Center said.

Tropical storm-force winds are expected to hit the area Saturday afternoon, while Ida is forecast to slam into the coast as a powerful Category Four hurricane - with winds up to 140 miles per hour - late Sunday.

Louisiana Governor John Bel Edwards said Ida would be one of the most powerful storms to hit the state since the 1850s.

In New Orleans, Mayor LaToya Cantrell warned residents to take Ida with utmost seriousness. "Time is not on our side," she told a briefing. "It's rapidly growing, it's intensifying."

Biden said hundreds of emergency personnel had been sent to the region, along with food, water and electric generators. Shelters were being prepared around the region, but Louisiana has been one of the hardest-hit states by the Covid-19 pandemic, and Biden urged anyone heading to a shelter to wear a mask and take precautions.

'BE READY FOR WHATEVER COMES': The dire warnings about Ida inevitably sparked memories of Katrina, Governor Edwards said in a briefing. "It's very painful to think about another powerful storm like Hurricane Ida, making landfall on that anniversary," he said.

One big difference, he said, was the huge investment since then in an extensive storm protection system of levees, gates and pumps. "Having said all that," he added, "this system is going to be tested (but) we're going to get through this." Meantime, a Category One hurricane named Nora was on a track threatening Mexico's central Pacific coast state of Jalisco, the NHC said. It warned of "life-threatening flash floods and mudslides."

Last week, a rare tropical storm struck the US northeastern seaboard, knocking out power, uprooting trees and bringing record rainfall. Scientists have warned of a rise in cyclone activity as the ocean surface warms due to climate change, posing an increasing threat to the world's coastal communities.