Hurricane Beatriz is threatening some of Mexico's most popular resorts, leaving tourists sheltering in their hotels.
The Pacific ports of Acapulco, Manzanillo and Zihuatanejo are closed.
The US National Hurricane Center said winds rose to 150km/h (90mph), with the storm moving over the coast.
The first Pacific hurricane formed earlier this month, causing no damage, but forecasters predict a busier hurricane season over the Atlantic.
So far casualties have been light. One tourist is reported to have been injured by a falling tree in Acapulco.
The Mexican government issued a red alert for areas around the resort city of Manzanillo.
And hurricane warnings were issued along coast from Lazaro Cardenas north to Cabo Corrientes.Tourists
Early on Tuesday, Beatriz was located about 20km (15 miles) south-east of La Fortuna and 80km (50 miles) west-northwest of Manzanillo, moving northwest at about 20 km/h (13mph).
It was expected to drop 15-30cm (6-12in) of rain along the coast, with a risk of flash floods and mudslides.
The category 1 hurricane is expected to weaken and move away from the coast by the end of Tuesday.