Communities along the west coast of Mexico are being evacuated as the nation braces itself for the arrival of the "strongest storm on record", Hurricane Patricia.
The central American country declared a state of emergency as Patricia, expected to have sustained winds of 200mph, barrelled towards the southwestern region.
A Category 5 storm, it will be the "strongest on record over the eastern North Pacific", according to the National Weather Service's National Hurricane Center .
Residents are fleeing their homes, many of which are being boarded up along with shops and business, along Mexico's coast.
It comes after experts warned Patricia could trigger 39ft waves and "life-threatening" flash flooding when it makes landfall this afternoon or tonight.
The U.N. World Meteorological Organization said Patricia was comparable to Typhoon Haiyan, which killed 6,300 people in the Philippines in 2013.
Patricia continued to strengthen overnight with maximum sustained winds of about 185mph, WMO spokeswoman Clare Nullis told a U.N. briefing in Geneva.
It strengthened into an "extremely dangerous" Category 5 storm late on Thursday as it churned toward Mexico's Pacific coast, the US NHC said.
The US government issued an advisory urging its nationals to steer clear of beaches and rough seas, and to take shelter as instructed by Mexican officials.
Some businesses in Puerto Vallarta, Mexico, had begun boarding and taping up windows late yesterdayas a precaution, while several domestic flights had been delayed.
Mexican emergency officials began to prepare shelters and warned people in the states of Colima, Jalisco and Michoacan to get ready for torrential rainfalls.
None of the major installations of Mexican state oil giant Pemex lie in the projected path of the storm.