Hurricane Willa has reached the maximum category 5 and is expected to make landfall on Mexico's Pacific coast late on Tuesday.
The storm now has maximum sustained winds of around 160mph (260kph) and is "potentially catastrophic", according to the U.S. National Hurricane Center (NHC).
The entity said on Monday that the hurricane could strengthen further before making landfall, but that it should start to weaken slightly on Tuesday.
However, it emphasized that it will be "extremely dangerous" when it reaches Mexico.
The storm is moving at 11 kph and should touch land on a stretch of the coast between Mazatlan and Puerto Vallarta.
Willa, which will arrive on the heels of tropical storm Vicente, is expected to result in intense storms in Nayarit, Jalisco, Colima, Michoacán, and Guerrero, as well as heavy rainfall in Sinaloa, Durango, and Baja California Sur.
These areas are known for their production of numerous fruit crops at this time of year including avocados, blackberries, and papayas.
According to the NHC, Willa will produce life-threatening storm surges with waves of up to six meters, with strong winds and rains in western and southwestern Mexico.
In that area, the effects of Willa could include total cuts of energy supplies, damage to roofs and floors of buildings that are up to 500 meters from the coasts.
The Mexican National Meteorological Service (SMN) indicated that "recent rainfall has softened the soil in some regions so there could be landslides, overflow of rivers and streams or effects on roads and road sections, as well as floods in low areas and saturation of drains in urban sites."