At one point a super typhoon and one of the strongest storms in the Pacific this year, Champi was still packing gusts of around 119 mph near its center, weather officials said.
Strong winds and coastal flooding are possible, but the storm is expected to stay far enough offshore that it will affect only the easternmost parts of the country.
The Mexican navy urged mariners and coastal residents to exercise extreme caution because of high waves, heavy rain and the risk of rising rivers, flooding and landslides in some areas.
The eye of the Category 2 hurricane remained offshore as its outer bands of wind and rain slammed communities between the Sierra Madre and the Pacific Ocean near Puerto Vallarta.
President José Antonio Kast declared a state of emergency for Las Condes, a wealthy suburb east of Santiago, giving government agencies more power to respond to torrential rains.