MIAMI, United States (AFP) – Hurricane Matthew rapidly gained power Friday, escalating to a powerful Category 4 storm as it moved over the open Caribbean sea just south of Jamaica, US forecasters said.

A hurricane watch was issued for Jamaica due to the approaching storm, and forecasters warned of tropical storm conditions for Haiti and Cuba over the next two days.

Packing wind speeds of 140 miles (220 kilometers) per hour, the storm moved in a western direction about 465 miles southeast of Jamaica.

The hurricane watch issued for Jamaica indicates that hurricane conditions are possible by Monday.

“Some additional strengthening is possible tonight,” said the National Hurricane Center.

“Matthew is expected to remain a powerful hurricane through Sunday.”

Matthew became a Category 1 hurricane on Thursday afternoon, the lowest on a 1-5 scale, then swiftly rose to Category 4 a day later.

Tropical storm warnings were issued for parts of coastal Colombia on Friday, with Haiti also bracing for tropical storm winds and rain by Sunday.

Forecasters said 10-15 inches (25-38 centimeters) of rain could fall on southern Haiti and across Jamaica.

Isolated areas could be lashed with up to 25 inches of rain, risking life-threatening flash floods and mud slides.

Ocean swells with the potential to cause dangerous currents and rip tides are also possible over the next two days in coastal regions of Puerto Rico, Venezuela, Aruba, Bonaire, Curacao, Colombia, the Dominican Republic and Haiti.