MEXICO CITY - Tropical storm Julia turned into a hurricane on Saturday evening as it passed the Colombian island San Andres and headed toward the Caribbean coast of Nicaragua with maximum sustained winds of 120kmh, the US National Hurricane Centre (NHC) said.

"Life-threatening flash floods and mudslides possible from heavy rains over Central America and Southern Mexico through early next week," the NHC said.

The storm is barrelling toward Nicaragua "in a hurry," NHC said earlier on Saturday.

The storm was 15km from San Andres island and about 225km from the Nicaraguan coast, where it is expected to make landfall overnight, according to the NHC.

Central American countries initiated emergency alerts ahead of Julia's arrival, just one week after Hurricane Ian pummelled Cuba and Florida.

Colombia President Gustavo Petro said in a speech at a regional summit on Saturday afternoon that he hoped "the damage would be less than last time", referring to the destruction in the Caribbean from Hurricane Iota in 2020.

He called on hotel chains to "open their doors for shelter".

After making landfall in Nicaragua, the hurricane is expected to gradually weaken as it crosses the country, before moving north along the Pacific coasts of Honduras, El Salvador and Guatemala on Sunday and Monday, the NHC said.

The storm could bring flash flooding to southern Mexico early next week, NHC said. REUTERS