Typhoon Megi is gathering strength as it moves toward China according to the latest forecasts, having left 200,000 people homeless in the Philippines.
Relief workers scrambled to deliver aid to remote towns that were devastated by the storm following the impact on Monday evening.
Some 19 people are feared to have died during the typhoon.
The governor of the hardest-hit province of Isabela, Faustino Dy said local residents in three coastal towns had suffered massive damage to their homes and were left with limited food supplies after huge waves washed away roads.
“Their food supply is only up to Sunday,” she continued.
Speaking from Cauayan, the closest city to the worst-hit towns, she added: “Going there is very difficult. There is no road to reach them.”
US ambassador Harry Thomas said in a statement US military personnel and equipment that was already in the Philippines for a joint exercise would be diverted for typhoon relief.
“My embassy team is in constant contact with Philippine authorities and NGO (non-governmental organisation) representatives to determine how we can be of further assistance,” read a statement issued by the embassy.
Megi smashed mostly farming and fishing areas of northern Luzon with gusts of 260 kilometres (160 miles) an hour on Monday, making it the strongest typhoon in the world this year.
Super Typhoon Megi lost power after slamming into the northern Philippines on Monday but was expected to build back up to super typhoon levels by Thursday.
At present authorities across southern China are preparing for the impact, with landfall expected on Saturday, the Hong Kong Observatory said.
In Guangdong, southern China, officials ordered all fishing boats to return by the end of Tuesday, put the provincial flood control headquarters on alert and warned reservoirs to watch their water levels, China’s official Xinhua News Agency reported.
In the southern island province of Hainan, residents in the provincial capital Haikou rushed to supermarkets to stock up on food, vegetables and bottled water, Xinhua said.