Hurricane Adrian has formed in the eastern Pacific, making it the first of the 2011 season, forecasters said Wednesday.
As a precaution, the Mexican government issued a storm watch for part of the country's coast, including the Pacific resort city of Acapulco.
Forecasters at the U.S. National Hurricane Center said the center was expected to remain offshore, but a shift could bring tropical storm conditions to the coast.
The Guerrero state government said thunderstorms and hail might hit about 20 coastal towns, where about 2 million people live. It urged people not to go out in the streets, if not necessary.
Adrian's maximum sustained winds were about 75 mph (120 kph) and it was expected to get stronger.
The center of the storm was about 265 miles (426 kilometers) south-southwest of Acapulco and moving northwest near 9 mph (15 kph).
The storm watch was in effect for Mexico's Pacific coast from Acapulco northwest to Punta San Telmo.