One of the most powerful Atlantic hurricanes in recent history weakened a little on Saturday as it roared across the Caribbean on a course that still puts Jamaica, Haiti and Cuba in the path of potentially-devastating winds and rain.
Matthew briefly reached the top hurricane classification, category five, and was the strongest Atlantic hurricane since Felix in 2007.
The US National Hurricane Centre in Miami said its winds had slipped to a still-devastating 155 mph and it was expected to reach the eastern part of Jamaica on Monday.
Jamaicans began clearing out shop shelves as they stocked up on emergency supplies and prime minister Andrew Holness on Friday called an urgent meeting of Parliament to discuss preparations for the storm.
"I left work to pick up a few items, candles, tinned stuff, bread," 41-year-old Angella Wage said at a crowded shop in the Half Way Tree area of the capital, Kingston. "We can never be too careful."
Evan Thompson, director of Jamaica's National Meteorological Service, said the first effects of the storm may be felt as early as Saturday. "We do consider it serious," Mr Thompson said. "We are all on high alert."
Jamaicans are accustomed to intense tropical weather but Hurricane Matthew looked particularly threatening. At its peak, it was more powerful than Hurricane Gilbert, which made landfall on the island in September 1988 and was the most destructive storm in the country's modern history.
"Hurricane Matthew could rival or possibly exceed Gilbert if the core of the strongest winds does actually move over Jamaica," said Dennis Feltgen, a meteorologist and spokesman for the hurricane centre in Miami. "There is no certainty of that at this point."
Matthew was expected to bring heavy rainfall especially to the eastern tip and higher elevations, which could trigger flooding and landslides, Mr Thompson said.
Forecasters said rainfall totals could reach 10 to 15 inches, with isolated maximum amounts of 25 inches in Jamaica and south-western Haiti.
Matthew caused at least one death when it entered the Caribbean on Wednesday, with officials in St Vincent reporting a 16-year-old boy was crushed by a boulder as he tried to clear a blocked drain.