Hurricane Michael has slammed into the Florida Panhandle with potentially catastrophic winds of 155 mph.

Michael blew ashore near Mexico Beach, a tourist town about half way along the Panhandle, a lightly populated, 200-mile stretch of white-sand beach resorts, fishing towns and military bases.

The storm is the most powerful hurricane to hit the US mainland in nearly 50 years.

Michael battered the coastline with sideways-blown rain, powerful gusts and crashing waves. It swamped streets, bent trees, stripped away limbs and leaves, knocked out power, shredded awnings and sent other building debris flying.

“The window to evacuate has come to a close,” Federal Emergency Management Agency administrator Brock Long said.

The storm went from a weekend tropical depression to Category 4 by early Wednesday, up from a Category 2 less than a day earlier. It was the most powerful hurricane on record to hit the Panhandle.

“I’ve had to take antacids I’m so sick to my stomach today because of this impending catastrophe,” National Hurricane Centre scientist Eric Blake tweeted as the storm grew more powerful.

Based on its internal barometric pressure, Michael was the most powerful hurricane to blow ashore on the US mainland since Camille in 1969.

Based on wind speed, it was the fourth-strongest, behind Andrew in 1992, Camille, and the biggest one of all, an unnamed 1935 Labour Day storm that had winds of 184 mph.

More than 375,000 people up and down the Gulf Coast were urged to evacuate as Michael closed in.

Hurricane-force winds extended up to 45 miles from Michael’s centre. Forecasters said rainfall could reach up to a foot, and the life-threatening storm surge could swell to 14 feet.

The storm appeared to be so powerful that it is expected to remain a hurricane as it moves over Georgia early on Thursday. Forecasters said it will unleash damaging wind and rain all the way into the Carolinas, which are still recovering from Hurricane Florence’s epic flooding.

National Hurricane Centre meteorologist Dennis Feltgen wrote on Facebook: “We are in new territory. The historical record, going back to 1851, finds no Category 4 hurricane ever hitting the Florida panhandle.”

Scientists say global warming is responsible for more intense and more frequent extreme weather, such as storms, droughts, floods and fires. But without extensive study, they cannot directly link a single weather event to the changing climate.