Flooding threat in Jamaica and Haiti from Hurricane Melissa

Hurricane Melissa is predicted to arrive in Jamaica on Monday (Matias Delacroix/AP)

A strengthening Melissa grew into a Category 4 hurricane and could reach Category 5 status by Sunday night, unleashing torrential rain and threatening to cause catastrophic flooding in the northern Caribbean, including Haiti and Jamaica, the US National Hurricane Centre said.

The weather agency added Melissa is likely to reach the southern coast of Jamaica as a major hurricane late on Monday or Tuesday morning, and urged people on the island to seek shelter immediately.