(CNN)Hurricane Matthew weakened as it churned across the Caribbean — threatening Jamaica, Cuba, Haiti and the Bahamas.
Matthew strengthened into a Category 5 late Friday, becoming the strongest hurricane in the Atlantic Ocean since Felix in 2007, the National Weather Service said.
However, by early Saturday, it had downgraded to a Category 4 hurricane with maximum sustained winds of 155 mph (250 km/h).
“Many land areas are at least threatened by the system,” said Rick Knabb, director of the National Hurricane Center. “Hurricane hunters are going to be flying in and out of Matthew for days to come.”
Knabb noted that south Florida could be threatened next week, but residents had “the luxury of time.” He urged people to use it to prepare and buy supplies.
CNN Weather said it is still unclear whether Matthew will hit Florida, where weather models currently have it possibly scraping. But by late Sunday or Monday, the dangerous storm should be approaching Jamaica, Haiti and eastern Cuba.
BC Airways has canceled all flights Monday to and from the American naval station at Guantanamo Bay, Cuba, because of the approaching storm, the naval station announced via Twitter.
American and Delta airlines issued travel warnings for their customers, saying change fees can be waived for flights to some destinations.
The storm was a Category 1 on Thursday. Early Friday, it was re-categorized as a Category 3 storm, before strengthening into Category 4 then 5.