The storm is seen as “potentially catastrophic” in its impact.
Mexican authorities have already been evacuating thousands of residents along the country’s Pacific coast.
The storm is comparable to Typhoon Haiyan, which killed 6,300 people in the Philippines in 2013, the World Meteorological Organization says.
A state of emergency has been declared in three states in Patricia’s path.
The storm is carrying winds of 305km/h (190mph). It made landfall in the Playa Perula area of Jalisco state, some 30km (20 miles) from the port city of Manzanillo.