MIAMI, Florida (CNN) -- Flooding and mudslides triggered by Hurricane Ida's torrential rainfall have killed at least 91 people in El Salvador, and the death toll is expected to rise, the government said Sunday.

As the storm -- which regained hurricane intensity overnight -- headed through the Yucatan Channel and into the Gulf of Mexico, a hurricane watch was issued Sunday for parts of the U.S. Gulf Coast.

Ida also drenched Nicaragua after making landfall last week as a Category 1 hurricane, then weakened to a tropical storm.

The U.S. watch -- meaning hurricane conditions are possible within 36 hours -- extends from Grand Isle, Louisiana, eastward to Mexico Beach, Florida, forecasters said. It does not include the city of New Orleans, Louisiana, the hurricane center said.

Track Ida's progress

The watch prompted Gov. Bobby Jindal to declare a state of emergency in Louisiana. The declaration frees the state's Office of Homeland Security and Emergency Preparedness to take certain measures to prepare for the storm and deal with it should it hit the state.

Ida was expected to brush the northeastern tip of Mexico's Yucatan Peninsula by Sunday afternoon.

As of 1 p.m. ET, Ida had reached Category 2 intensity, with maximum sustained winds of near 100 miles per hour (160 kilometers per hour) and higher gusts. Some additional strengthening was possible Sunday, but the storm was expected to weaken on Monday and begin losing tropical characteristics on Tuesday, the hurricane center said.

The center of Ida was located about 100 miles (155 kilometers) north-northeast of Cozumel, Mexico, and about 75 miles west of the western tip of Cuba, forecasters said. It was moving northwest at near 10 mph and was expected to increase in speed and turn toward the north-northwest later, then northward by Tuesday.

"On the forecast track, the center of Ida should move into the Gulf of Mexico this afternoon and be near the northern Gulf Coast by Tuesday," the hurricane center said.

Once Ida moves into the Gulf of Mexico, conditions are expected to be unfavorable for any additional development, said CNN meteorologist Dave Hennen. Ida is expected to weaken because of a combination of wind shear, cooler water temperatures and the storm's interaction with a strong frontal system pushing off the Gulf Coast, he said.

However, Ida still could bring heavy rain to the Gulf Coast and parts of the Southeast, he said.

A hurricane warning remained in effect on the Yucatan Peninsula from Playa del Carmen to Cabo Catoche, meaning that hurricane conditions are expected in the warning area within 24 hours, the National Hurricane Center said. A hurricane watch remained in effect for the peninsula from Tulum to Playa del Carmen.

A tropical storm warning was in effect for the Yucatan from Punta Allen north to Playa Del Carmen and from Cabo Catoche west to San Felipe, forecasters said. In addition, a tropical storm warning was in effect for the Cuban province of Pinar del Rio. A tropical storm warning means that tropical storm conditions are expected within 24 hours.

A tropical storm watch remained in effect for the Isle of Youth, forecasters said.

Ida could bring between 3 and 5 inches of rain to portions of the Yucatan Peninsula and western Cuba, with isolated amounts of 10 inches possible in some spots, forecasters said. In addition, a storm surge could raise water levels by 3 to 4 feet along the coast of the Yucatan, forecasters said. "Near the coast, the surge will be accompanied by large and destructive waves," the hurricane center said.

Ida is the Atlantic region's ninth named storm. The Atlantic hurricane season ends November 30.

CNN meteorologist Jacqui Jeras and journalist Merlin Delcid in El Salvador contributed to this report.