“We must therefore brace ourselves for the possible effects of a typhoon of this magnitude,” Executive Secretary Salvador Medialdea said in a statement.
Haima is expected to be the second powerful storm to pound the Philippines this week.
It is blasting the Philippines with strong winds and heavy rainfall that could trigger landslides in the mountainous region of the northern island of Luzon.
The effect of the storm, known as Lawin in the Philippines, will depend on where it makes landfall, CNN meteorologist Taylor Ward said.
“The area around the center will have extreme damage from the winds as well as a significant storm surge,” he said.
The storm is on track to hit the north of Luzon midnight local time Wednesday into Thursday morning.
The storm surge and winds near the center of Haima will be catastrophic, but the area of the coastline it’s expected to hit is sparsely populated.
The typhoon is expected to hit as many as 2.7 million people across seven Philippine provinces.
Haima is then expected to veer northwest and hit the Chinese coast by Friday evening.
“Current projections take the storm into eastern Guangdong province, to the east of Hong Kong, but we will keep a close eye on Hong Kong in the coming days as some models take the storm fairly close,” Ward said.
The storm will be much weaker by that point, though flooding could still occur.
And according to data going back to 1950 from the Joint Typhoon Warning Center, it will be just the third time back-to-back storms with an intensity of Category 4 or above have hit the Philippines.
At least three people were killed Sunday as Typhoon Sarika crossed the archipelago north of Manila as a Category 4 storm. Almost 10,000 people were displaced, according to aid organization Care International.
On Tuesday, that weather system made landfall on the southern Chinese island of Hainan, prompting the government to close schools in the island province and suspend high-speed rail services, China’s state-run Xinhua news agency reported.
About 500,000 people were evacuated in advance of the storm, Xinhua reported.
CNN’s Katie Hunt, Serenitie Wang and Reed Alexander contributed to this report.