Melissa strengthened into a major Catergory 3 hurricane late Saturday as it unleashed torrential rains over northern Caribbean, threatening "catastrophic flash flooding" in the region.

US weather forecasters warned that the storm will rapidly intensify over Sunday and make landfall in Jamaica early next week. It could turn into a Category 4 hurricane by Tuesday before likely moving into eastern Cuba on Wednesday.

"Life-threatening and catastrophic flash flooding and landslides are expected in portions of southern Hispaniola and Jamaica into early next week," the US National Hurricane Center said Saturday evening. 

In its latest update, the Center said that the hurricane had maximum sustained winds of 115 mph (185 kph) — faster than the previously reported 100 mph (155kph).

"Rapid intensification is expected to continue for the next 24-36 hours, and it is possible that during this time Melissa could intensify even faster than what is currently forecast," the US National Oceanic and Atmospheric Administration said.

"I urge Jamaicans to take this weather threat seriously," Jamaican Prime Minister Andrew Holness had said earlier on Saturday. "Take all measures to protect yourself."

Deadly Melissa Kills at least four

The southern regions of Haiti and the Dominican Republic will also face torrential rainfall through Monday.

Melissa has already caused three deaths in Haiti. Two people were killed in a landslide on Thursday and a third died after a tree fell on them amid heavy rain earlier in the week.

A fourth person has been killed in the neighboring Dominican Republic, where another person remains missing.

Nearly 200 homes in the Dominican Republic have been destroyed, while water supply to more than half a million people has been disrupted.

Melissa is the 13th named storm of the Atlantic hurricane season, which runs from June 1 to November 30. Weather experts have predicted an above-normal season this year with up to 18 named storms.

Edited by: Jenipher Camino Gonzalez