PThe Hilippin government spokesman Ariel Rojas said that although the storm overtook the Philippines, it would continue to cause heavy rains in the country, which could cause further flooding and landslides by Monday.
But the storm probably would not get stronger, Rojas said.
"It could probably maintain or even weaken its current intensity," he told AFP.
The Hong Kong government said Mangkhut will pose "a serious threat to the region." Many residents in the city and neighboring Macau have supplied themselves with food and supplies.
Volunteers also helped the residents of the low-lying Hong Kong fishing village of Tai O to raise their furniture and equipment to higher ground.
Tsai Ing-wen, the president of Taiwan, told the citizens that they would be ready when powerful waves shook the shore.
"The typhoon is powerful and even (if) it is not expected to land in Taiwan, we should be well prepared and not … take it lightly," she wrote on Facebook.