NEW ORLEANS (BLOOMBERG) - Hurricane Zeta is walloping New Orleans with the most powerful winds since Katrina devastated the city in 2005, blacking out tens of thousands of homes and businesses, knocking out traffic lights and triggering voluntary evacuations.

Zeta made landfall near Cocodrie, Louisiana, with winds of 175 kmh on Wednesday (Oct 28), becoming the fifth hurricane or tropical storm to hit the state this year, the National Hurricane Centre (NHC) said.

Never before have so many major storms smashed into Louisiana or the contiguous US in a single season, according to Phil Klotzbach, a hurricane researcher with Colorado State University.

While Zeta isn't as powerful as Katrina, it is running directly over the Crescent City, bringing the harshest winds in 15 years. By moving at a brisk 38 kmh, it could pass over quickly enough to spare New Orleans catastrophic flooding. Damages may still total as much as US$5 billion (S$6.8 billion).

At 177 kmh, Zeta is just shy of being a major Category 3 hurricane.

"This is going to be one of the worst hurricanes to hit New Orleans proper since Katrina," said Jim Rouiller, chief meteorologist at Energy Weather Group LLC.

Zeta is the latest in a grim parade of natural disasters to hit the US in recent months as climate change makes weather increasingly extreme.

In California, heat waves, drought and violent winds have combined to fuel a rash of wildfires that have burned a record 1.66 ha this year. And along the East and Gulf coasts, a record 11 named storms have hit the US, with five battering Louisiana alone.

In all, 27 storms have formed across the Atlantic in 2020. So many systems have formed this season that the NHC has used up all its official titles and has resorted to the Greek alphabet to designate new ones.

The eye of the storm was moving into New Orleans by about 7pm New York time, the city's emergency response agency said on Twitter.

More than 280,000 homes and businesses across Louisiana lost power within hours. The electrical failures knocked out traffic lights, and government officials warned residents to stay off the roads.

Zeta becomes only one of six storms to hit the US this late in October and the first hurricane to do so since 1985, said Jeff Masters, a meteorologist with Yale Climate Connection. While Sandy was a powerful storm when it came ashore in New Jersey in 2012, it had lost its hurricane characteristics when it struck land.

Rapid Intensification

Zeta grew in strength as it moved across the Gulf, and all told this year six storms have rapidly intensified - short of a record, but indicative of climate change.

"There have been a lot of rapidly intensifying storms and that is something we expect to see in a warming climate," Masters said.

Zeta may cause as much as US$5 billion in damages and losses, said Chuck Watson, a damage modeller at Enki Research, who raised his estimate from an initial US$1 billion as the forecast worsened. The storm's stronger winds bring more dynamic pressure on everything it hits, and there are simply more targets in the way the closer to New Orleans it gets.

While the intensity and number of storms has surpassed the 12 that usually form in an average season, there is no indication things will stop as October ends and November begins. A potential storm could form in the Caribbean Sea within the next week, which would be called Eta. This would be the 28th storm and tie a record with 2005 for the most in a single year.

Not Done Yet

There might even be more. A global weather pattern called the Madden Julian Oscillation that's about to exert its influence on the Atlantic may spark a spate of storms.

The Atlantic is still warm enough to spin up hurricanes and there are still plenty of tropical waves, the building blocks of hurricanes, emanating from Africa, Masters said. In addition, autumn cold fronts moving off North America often swirl into tropical storms.

"I suspect we will see one or two of those this year," Masters said. "Thirty storms are possible."