Floods and mud slides have killed 91 people, as heavy rains from Hurricane Ida hit El Salvador, the country's interior minister has said.

Humberto Centeno said 60 people are still missing, and about 7,000 more are in shelters.

He told reporters that many towns are still cut off, and that officials have been unable to reach them.

The capital of San Salvador and central San Vicente province are the hardest-hit regions.

Ida strengthened to a category 2 storm today, and a hurricane watch was extended to the Florida Panhandle as Ida made its way across the Gulf of Mexico.

The hurricane watch now stretches from southeastern Louisiana to Mexico Beach. Forecasters at the US National Hurricane Centre in Miami said Ida's winds are now near 100mph , meaning Ida could get stronger.

The watch means hurricane conditions are possible in the next 36 hours.

The hurricane was moving to the northwest near 10mph, with Ida expected to pick up steam as it moved over open waters in the Gulf of Mexico.

Ida could reach the Gulf Coast by Tuesday, though it was unclear how strong it would be by then.

Earlier today, Ida's wind and rain whipped palm trees in the Mexican resort of Cancun. Fishermen tied their boats down, though tourists seemed to regard Ida as only a minor setback.

"I figure probably in a couple hours we'll be stuck inside," said Julie Randolph, 40, a social worker from Ormond Beach, Florida, who braved the rain to jog along the near-empty beach.

As winds picked up and intermittent rains intensified this morning, restaurants and nightclubs near the waterfront began covering their windows with large pieces of plywood.

Ida is expected to interact with a weakening cold front over open seas and will most likely be a tropical storm or perhaps a low-level hurricane when it gets to the Gulf Coast.

Parts of the Yucatan Peninsula remained under a hurricane warning, and a tropical storm warning was in place for the western tip of Cuba with heavy rains expected.