Hurricane Willa has grown into a "potentially catastrophic" Category 5 storm in eastern Pacific Ocean, on a path to pummel Mexico's western coast between late Tuesday and early Wednesday.
Earlier this month areas of the U.S. were devastated by Hurricane Michael, which left at least 27 people dead.
A hurricane watch was posted for a stretch of shore between San Blas and Mazatlan, while a tropical storm warning was in effect from Playa Perula to San Blas.
The major resort areas of Puerto Vallarta and Mazatlan are under tropical storm warnings - as they are expected to face gusty winds, heavy rain and some flooding - but they are not under hurricane warnings, because the worst part of the storm is forecast to miss those popular vacation spots.
By early Monday, Willa had maximum sustained winds of 160mph - the same wind speed Hurricane Michael had at landfall in Florida - and was centered 135miles south-southwest of Cabo Corrientes.
The storm is forecast to hit the area on October 23 before moving over central Mexico. The storm is moving north-northwest at 7 miles per hour, according to the NHC's latest advisory.
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Hurricane Willa has quickly strengthened into a deadly Category 4 storm and will intensify further this week in wake of low wind shear and warm water temperatures.
Willa is expected to reach category 5 status on Monday - the highest classification for hurricanes.
Meanwhile, Tropical Storm Vicente, which formed in the Pacific off southern Mexico on Saturday, began to weaken as it hovered along the coast of southern Mexico on Sunday, located about 230 miles south-east of Acapulco.
According to the NHC, "A west-northwestward turn is expected later this morning, followed by a turn toward the northwest by late tonight".
On the other hand, the hurricane Vicente would stay offshore or near the southern coast of Mexico, weakening to a tropical depression through Tuesday morning. "The cyclone's circulation is expected to dissipate near the southwestern coast of Mexico by Wednesday".