(Updates with location of storm in paragraph 2, details in paragraph 8)
By Rebekah Kebede
KINGSTON, Jamaica, Sept 30 (Reuters) - Hurricane Matthew surged in power on Friday to become the Caribbean's strongest storm in nine years as it moved towards Jamaica and Cuba with winds of up to 160 miles per hour (260 kph) powerful enough to wreck houses, forecasters said.
Matthew was about 430 miles (690 km) southeast of Kingston, Jamaica, and the U.S. National Hurricane Center (NHC) designated it as a Category 5, the strongest on the Saffir-Simpson scale of hurricane intensity.
The strongest hurricane in the Atlantic Ocean since Felix in 2007 was forecast to make landfall as a major storm on Monday on Jamaica's southern coast, home to the capital and Jamaica's only oil refinery. It could affect the island's main tourist areas such as Montego Bay in the north.
"The government is on high alert," said Robert Morgan, director of communications at the prime minister's office.
"We hope that the hurricane does not hit us, but if it does hit us, we are trying our very best to ensure that we are in the best possible place."
Local disaster coordinators, police and military have been put on standby and shelters are being opened throughout the island, Morgan said.
Despite the sunny weather and only a few scattered clouds, many Kingstonians were stocking up on water and food on Friday in preparation.
The center of the storm will move away from the Guajira Peninsula early Saturday morning, across the central Caribbean Sea on Saturday and approach Jamaica late on Sunday, the National Hurricane Center said.
Jamaica was hard hit by hurricane Gilbert in 1988, and the last major hurricane in the region was Sandy, in 2012. Matthew could be the most powerful storm to cross the island since records began, meteorologist Eric Holthaus said on Twitter.
Tenaj Lewis, 41, a doctor who was stocking up at the MegaMart grocery store in Kingston on Friday afternoon said Jamaica was much better prepared for hurricanes than when Gilbert hit.
"The country literally shut down for months," she said.
Since then, hurricanes have brought a few days of power outages but have not been nearly as destructive.
Some residents were enjoying the calm before the storm.
Peter Silvera, who owns the Longboarder Bar & Grill in the Roselle, a small hamlet on the southeastern coast of the island, said he was surfing all morning.
"This is when we get the best waves," he said, but added he would be bringing in his outdoor tables and "battening down the hatches" to ride out the storm.
"I think we're probably going to get a square hit," he said.
As a precaution, Southwest Airlines warned that flights to Montego Bay could be disrupted and said customers could reschedule.
Matthew is also forecast to skim past the south coast of Haiti on Monday bringing tropical storm conditions.
Haiti has been hard hit by natural disasters in the past, and officials said preparation efforts were focused in the south of the country.
"We will prepare with drinking water for the patients, with medication, with generators for electricity, available vehicles to go look for people at their homes," said Yves Domercant, the head of the public hospital in Les Cayes in the south.
In Cuba, which has a strong track record of keeping its citizens out of harm's way when storms strike, residents of the eastern coastal city of Santiago de Cuba said they were tracking the news closely, although skies were still blue.
"We don't know yet exactly where it will go, so we're still waiting to see," said Marieta Gomez, owner of Hostal Marieta, who was following the storm closely on TV and radio. "We Cubans are well prepared."
The storm killed one person in St. Vincent and the Grenadines earlier in the week. (Addtional reporting by Makini Brice in Port-Au-Prince, additional reporting by Sarah Marsh in Havana and Vijaykumar Vedala in Bengaluru; Writing by Frank Jack Daniel; Editing by Grant McCool, Sandra Maler and Christian Schmollinger)