The most powerful typhoon of the season is closing in on the northern Philippines, where officials ordered precautionary evacuations and closures of schools and offices and urged farmers to quickly harvest their crops to reduce damage.

Forecasters said Typhoon Mangkhut could hit northern Cagayan province on Saturday.

It was located about 500 miles away in the Pacific with sustained winds of 165 mph and gusts of up to 201 mph. It could maintain the strength of a super typhoon when it hits land in the northeastern corner of Luzon Island.

On Guam, residents woke up on Tuesday to flooded streets, downed trees and widespread power outages after Mangkhut passed through overnight.

The Pacific Daily News reported government agencies were conducting damage assessments and beginning to clear roads. About 80 per cent of the US territory was without power but it was restored by Thursday morning.

On Wednesday, food and water supplies were delivered to the island on the world's biggest plane, the Antonov Airlines AN-255.

The Ukraine-based cargo airline required special permission for the trip from the US Department of Transportation. According to its application last week, the airline stated "civil aircraft operated by US carriers are apparently not available to meet FEMA's requirements".

Rescuers ready their gear before Super Typhoon Mangkhut hits the main island of Luzon, in Manila (Reuters)

With a massive rain band 560 miles wide, combined with seasonal monsoon rains, the storm could bring heavy to intense rains that could set off landslides and flash floods, Philippine state forecaster Meno Mendoza said.

Cagayan governor Manuel Mamba said northern coastal and island villages in the typhoon's projected path will begin evacuating residents on Thursday ahead of the expected onslaught.

He said classes will be suspended and offices, except those involved in rescue and relief work, are advised to close on Friday.

Hurricane Florence: New satellite video shows storm raging as it heads toward US east coast

In 2016, a super typhoon lashed the southern section of Cagayan, destroying tens of thousands of houses. Mangkhut is blowing from the Pacific and forecast to directly slam the province's northeastern coastal and island municipalities, Mr Mamba said.

"I'm stressing that this one is very different, this is more complicated because of possible storm surges," Mr Mamba said, referring to giant waves whipped inland by a typhoon.

The typhoon is arriving at the start of the rice and corn harvest season in Cagayan, a major agricultural producer, and farmers were scrambling to save what they could of their crops, Mr Mamba said. The Philippines has been trying to cope with rice shortages.

Hurricane Florence hits the US East Coast Show all 20 1 /20 Hurricane Florence hits the US East Coast Hurricane Florence hits the US East Coast Barmen protect their business from the storm and the opportunists Getty Hurricane Florence hits the US East Coast Many supplies have run out as Hurricane Florence approaches in Nichols, South Carolina AP Hurricane Florence hits the US East Coast Hurricane Florence seen from space on September 12 AP Hurricane Florence hits the US East Coast Students of East Carolina University's Coastal Storms class use anemometers to measure wind speeds at Union Point Park in New Bern, North Carolina AP Hurricane Florence hits the US East Coast Rescue workers are on the scene in James City, North Carolina Getty Hurricane Florence hits the US East Coast Sixteen hours before Florence even hits land, the Neuse River bursts its banks and floods New Bern, North Carolina Alamy Hurricane Florence hits the US East Coast Volunteer rescue workers help three children out of their flooded home in James City, North Carolina Getty Hurricane Florence hits the US East Coast A boardwalk is damaged in Atlantic Beach on North Carolina's coast Getty Hurricane Florence hits the US East Coast Union Point Park in New Bern is closed Reuters Hurricane Florence hits the US East Coast A child sits in Conway High School, which is being used as an evacuation centre in South Carolina AFP/Getty Hurricane Florence hits the US East Coast Locals voice their disapproval of the storm in Atlantic Beach, North Carolina Getty Hurricane Florence hits the US East Coast Volunteer rescue workers help children from their flooded home in James City Getty Hurricane Florence hits the US East Coast A man floats down his street in a metal tub after the Neuse River burst its banks in New Bern, North Carolina Getty Hurricane Florence hits the US East Coast Electric lines are affected in Wilmington, North Carolina Alamy Hurricane Florence hits the US East Coast Floods in New Bern, North Carolina as Florence approaches Alamy Hurricane Florence hits the US East Coast Waves crash over a pier on Atlantic Beach in North Carolina as Hurricane Florence approaches AP Hurricane Florence hits the US East Coast Hurricane Florence is seen from the International Space Station as it churns in the Atlantic Ocean towards the east coast of the US NASA/Reuters Hurricane Florence hits the US East Coast This NOAA/RAMMB satellite image taken on September 10, 2018, shows Hurricane Florence off the US' east coast in the Atantic Ocean AFP/Getty Hurricane Florence hits the US East Coast In this NOAA satellite handout image, Hurricane Florence is shown travelling west and gaining strength in the Atlantic Ocean southeast of Bermuda on September 10, 2018 Getty Hurricane Florence hits the US East Coast Firefighters rescue people by boat in New Bern, North Carolina Getty

Ricardo Jalad, head of the Office of Civil Defence, said other northern provinces will also start evacuating residents from low-lying areas on Thursday.

"The worst cases are those areas which will be directly hit by strong winds that can topple houses, storm surges and heavy rains that can cause flooding, and there may be landslides in higher areas," Mr Jalad told reporters.

A missile test aboard a navy ship to be attended by President Rodrigo Duterte off northern Bataan province was cancelled due to the approaching typhoon.

After leaving the Philippines, the fast-moving storm is expected to blow towards Hong Kong and southern China on Sunday if it maintains its course, forecasters said.

Mangkhut is the 15th storm this year to batter the Philippines, which is hit by about 20 a year and is considered one of the world's most disaster-prone countries. Typhoon Haiyan left more than 7,300 people dead or missing and displaced over five million in the central Philippines in 2013.