Hurricane Otis strengthened from a tropical storm to a dangerous Category 5 hurricane in a matter of hours on Tuesday as it approached Mexico’s southern Pacific coast.

It is forecast to make landfall near the resort of Acapulco early on Wednesday causing catastrophic damage.

The US National Hurricane Centre said Otis has maximum sustained winds of 160mph as of late Tuesday evening. It was centred about 55 miles south-southeast of Acapulco.

A hurricane warning was in effect from Punta Maldonado to Zihuatanejo. A hurricane watch is in effect from Lagunas de Chacahua to Punta Maldonado.

Otis is forecast to remain a Category 5 hurricane through landfall but rapid weakening is then forecast due to the higher terrain of Mexico. Otis will likely dissipate over southern Mexico on Wednesday night.

In Acapulco, people hurried home as rain began to pelt the resort and winds picked up, driving tourists from the beach.

The Guerrero state government said it was preparing 396 shelters in anticipation of families being driven from their homes by wind damage or surging waters.

Mexico’s army and navy deployed more than 8,000 troops to the area with specialised equipment to aid in rescues. Authorities closed Acapulco’s port, home to some 300 fishing boats.

Otis was expected to dump five to 10 inches of rain on Guerrero, with as much as 15 inches possible in some areas. That raised the possibility of mudslides and flash floods in Guerrero’s steep mountainous terrain.