Hurricane Matthew battered Florida with destructive force early Friday as its eyewall brushed Cape Canaveral on its northward path — leaving more than 300,000 people without power after claiming at least 339 lives in Haiti.

The Category 3 storm — the first major hurricane threatening a direct hit on the US in more than a decade — unleashed its fury as it crept north-northwest at 14 mph while centered about 25 miles east of the cape about 6:30 a.m.

“We are just bracing and the winds are picking up,” Daytona Beach Mayor Derrick Henry told CNN early Friday. “A great number of our residents have taken heed to our warnings and we are certainly concerned about those that have not.”

The storm — which was downgraded from a Category 4 on the five-step Saffir-Simpson scale — is still very powerful, packing dangerous winds of 120 mph, according to the US National Hurricane Center, which warned of “potentially disastrous impacts.”

The US National Weather Service said Matthew, though expected to weaken in the next 48 hours, could be the most powerful to strike northeast Florida in 118 years.

A dangerous storm surge was expected to reach up to 11 feet along the Florida coast, Ed Rappaport, deputy director of the Miami-based NHC, told CNN.

“What we know is that most of the lives lost in hurricanes is due to storm surge,” he said.

In addition to the fatalities in Haiti, four people were killed in the neighboring Dominican Republic, Reuters reported. Thousands of residents in the Caribbean have been displaced.

It was too early to predict where Matthew might do the most damage in the US, but hurricane warnings reached up the Atlantic coast from southern Florida through Georgia and into South Carolina.

Weather experts were watching for any deviations in Matthew’s unpredictable path, which could make a huge difference to the hurricane’s impact on land.

“The exact path is so critical,” CNN meteorologist Derek Van Dam said. “Miles and kilometers really count, because if it wobbles westward by, say, 30 miles, it brings those strong winds onshore.”

More than 12 million people are under hurricane watches and warnings, according to the Weather Channel.

South Florida escaped much of Matthew’s wrath after the storm took an unexpected turn near Andros Island that pushed it farther north and east, the Miami Herald reported.

“This little twist did keep the center of the hurricane further way from South Florida and that has so far reduced the amount of wind and rain,” National Hurricane Center specialist Jack Bevin told the paper.

Hundreds of thousands of people heeded warnings and fled the danger zones, but other Floridians decided to ride it out along highly susceptible beachfronts from Brevard to Volusia County, the Herald reported.

Authorities urged 17,000 people in Martin County to leave barrier islands, but many held firm.

“My biggest concern is people aren’t taking this seriously enough,”’ Gov. Rick Scott said. “I don’t want people to lose their life.”

In Melbourne, residents were anxious — yet reluctant to leave.

“I’m worried. They’re telling us this is going to be the worst one we’ve ever seen,” Marion Smith, 76, told the paper.

The last major hurricane — classified as a storm with sustained winds of more than 110 mph — to make landfall on US shores was Hurricane Wilma in 2005.

At Palm Bay’s Tropical Inn Resort, some pooh-poohed the warnings.

“I don’t think it’s going to be a big deal,” said Allen Briggs, 43, whose family has lived in the region since the 1880s. “You know how the news is, always making a big deal out of it. I’m not worried.”