The storm was due to come ashore after lunch on Tuesday just south of Mazatlan, a popular beach resort
Hurricane Willa, an extremely dangerous a Category 4 storm, weakened slightly as it veered toward popular tourist resorts on Mexico's Pacific coast on Monday, prompting government warnings for people to evacuate high-risk areas and take cover.
Mexican authorities urged residents to evacuate to temporary shelters, closed ports, cancelled classes and suspended beachside and marine activities.
The storm was due to come ashore after lunch on Tuesday just south of Mazatlan, a popular beach resort in the northwestern state of Sinaloa. Several other tourist destinations also lie near to the storm's path.
Willa, which earlier in the day had been a Category 5 on the five-step Saffir-Simpson scale, was blowing maximum sustained winds of near 155 miles per hour (250 kph) by mid-afternoon with higher gusts, the Miami-based US National Hurricane Center (NHC) said.
Complete power outages, damage to roofs and even the foundations of buildings that are up to 500 meters (1,640 feet) from the coastline were possible, Mexico's National Meteorological Service (SMN) said.
Alberto Hernandez, head of the SMN, said the storm would probably be a Category 4 or 3 hurricane when it reached land, and could cause waves several meters (feet) high.
It could also lead to the formation of waterspouts in front of the coast of Puerto Vallarta, the SMN said, referring to another beach resort in the state of Jalisco.
Nearly three years ago to the day, Hurricane Patricia, one of the most powerful storms on record, struck Mexico close to Puerto Vallarta with winds that tore down trees, moved cars and forced thousands of people to flee homes.
Speaking in the western city of Guadalajara, President Enrique Pena Nieto warned the population to prepare for the arrival of Willa and urged residents to take cover.
The storm was about 110 miles (175 km) west-southwest of the town of Cabo Corrientes and is "expected to be a dangerous major hurricane when it reaches the coast of Mexico" the NHC said.
Willa is moving northward and is forecast to gradually lose power during the next day or so and weaken rapidly after hitting the coast.
The SMN urged residents to "exercise extreme caution" as rains have softened the soil in some areas. Willa's downpours could cause landslides, flooding and damage to roadways.
The NHC said that the Air Force Reserve Hurricane Hunter Aircraft that was en route to Willa experienced a safety issue before entering the storm and had to return to base.
Willa is expected to douse coastal states Jalisco, Nayarit and Sinaloa with 6 to 12 inches (15 to 30 cm) of rain, likely triggering flash floods and landslides, the NHC said. Some areas may see as much as 18 inches of rainfall.
To the south, Tropical Storm Vicente weakened further, with maximum sustained winds of 40 mph (65 kph). It was churning some 310 miles (500 km) southeast of the Pacific port Manzanillo.
While Vicente is expected to weaken to a tropical depression by Monday night or Tuesday, it could produce major rainfall and the risk of flash floods and landslides, the NHC said.