Officials readied storm shelters along Mexico's Caribbean coast Saturday and told fishermen and tour operators to pull in their boats amid warnings that Tropical Storm Ida could become a hurricane as it neared the resort city of Cancun.

The U.S. National Hurricane Center in Miami said Ida's winds strengthened to near 70 mph (110 kph), just short of a Category 1 hurricane. A tentative forecast track predicted Ida could brush the U.S. Gulf Coast next week as a tropical storm.

Tropical-storm warnings were issued for the Mexican coastline from Punta Allen, south of Tulum, to San Felipe at the top of the Yucatan Peninsula, an area that includes Cancun. The warnings were also in effect for western Cuba and Grand Cayman Island.

A hurricane watch was in effect from Tulum to Cabo Catoche.

As rain began pelting down in Cancun, the beaches were empty but tourists walked the streets under umbrellas or improvised rain ponchos.

"We are on yellow alert but the tourists are walking around normally in the streets and the shopping centers," said policeman Marco Morales Rodriguez.

Authorities started up a reporting system used to locate tourists and plan potential evacuations or shelters. Quintana Roo state Tourism Director Sara Latife Ruiz said there were about 36,000 foreign and Mexican tourists in Cancun.

"We can locate them and if necessary, take them to some temporary shelter," said Latife Ruiz. "Right now, no flights have been canceled ... and there has been no evacuation of tourists."

State civil defense Director Luis Carlos Rodriguez said "there is still time to protect property, so we have advised fishermen, small boat owners and those living in low-lying areas of Tulum, Holbox, Cancun and Playa del Carmen to take safety measures for their property."

Juan Granados, assistant director of civil defense, said the state was on yellow alert and that Ida was also expected to brush the nearby island tourist destinations of Cozumel and Isla Mujeres.

Saturday afternoon, Ida was centered about 200 miles (325 kilometers) east-southeast of Cozumel and moving north at about 10 mph (17 kph). It was projected to pass the tip of the Yucatan Peninsula on Sunday.

Granados said seven storm shelters were being readied on Cozumel, five on Isla Mujeres and seven on Holbox, an island north of the peninsula. Statewide, dozens more were being readied for use if needed.

Authorities suspended fishing along part of the coast and told tour operators who offer reef snorkeling and diving excursions to stay in port, Granados added.

Popular Mayan sites such as the seaside ruins of Tulum were to remain open, but employees worked to clean up debris that could become a hazard in high winds, Mexico's National Institute of Anthropology and History said in a statement.

John Cangialosi, a specialist at the Hurricane Center, said that as Ida heads north across the Gulf of Mexico, it is expected to meet a cold front that is moving south - making longer-term forecasts complicated for now.

"There's going to be some sort of interaction between the two, but where they interact, and how, and the timing of the thing, that's kind of the big question mark," Cangialosi said.

Regardless of how the cold front affects the tropical system, Cangialosi said residents on the north Gulf Coast can expect lots of wind and heavy rain.

Ida plowed into Nicaragua's Atlantic coast on Thursday as a Category 1 hurricane, damaging 500 homes along with bridges, power lines, roads and public buildings.

Cuba's national Meteorological Center said it did not expect any direct impact from the storm, but noted it could cause heavy rains in the western province of Pinar del Rio.