Patricia is packing maximum sustained winds of 120 kilometres per hour and is located 365 kilometres southwest of resort town of Acapulco, the US Hurricane Center in Miami said.
The hurricane is moving west-northwest at a speed of 26 kilometres per hour, the centre said.
According to current forecasts, the centre of the storm should approach the coast of southwestern Mexico tomorrow.
It is expected to become a major hurricane that day.
Patricia is forecast to produce total rain accumulations of six to 12 inches (152 to 304 mm), with isolated maximum amounts of 20 inches, over the states of Jalisco, Colima, Michoacan and Guerrero from today into Saturday.