Hurricane Erick makes landfall in Mexico's Oaxaca state
A hurricane warning is in effect for a 500km-stretch (300 miles) of the Pacific coast, from the resort town of Acapulco to Puerto Ángel.
Residents in Guerrero and Oaxaca have been warned of dangerous swells and torrential rain.
"If you are in low-lying areas, near rivers, near waterways, it is best for you to go to shelters, to the shelters that have already been set up for this situation," Mexican President Claudia Sheinbaum said.
People living in mountainous areas have been told to beware of possible mudslides.
Around 2,000 shelters have been set up across the states of Chiapas, Guerrero, and Oaxaca and more than 18,000 first responders have been mobilised to prepare for the hurricane.
The area was severely battered by Hurricane Otis in 2023. At least 50 people were killed when the Category-5 hurricane battered Acapulco.
Otis intensified rapidly, meaning many people were unprepared when the hurricane made landfall.