Heavy rain and howling winds are lashing the northern Philippines and Taiwan as Typhoon Usagi moves through the Luzon Strait dividing the two territories.
Meteorologists say the storm - the most powerful of the year to date - is bringing a cumulative rainfall of 1000mm as it heads towards China.
Villages have been evacuated, ferries suspended and flights cancelled, the BBC reports.
The authorities in China have announced a red alert ahead of the expected arrival of the storm on Monday.
The US Navy's Joint Typhoon Warning Centre said on Friday that Usagi was packing sustained winds of 240 km per hour with gusts of up to 296 km per hour, making it the equivalent of a strong category 4 Atlantic hurricane.
Taiwan is reported to have deployed more than 1,600 soldiers in "high risk" areas prone to flooding and landslides while placing 24,000 others on standby.
Authorities in the Philippines are reported to have evacuated nearly 250 people in the northern agricultural province of Tarlac, while ferries are restricted to their ports.
There are particular concerns about the impact of the storm on the Batanes islands in the north of the Philippines, with warnings that large trees could be uprooted, plantations flattened and power and communications severely disrupted by flash flooding, landslides and storm surges.