Wipha, a woman's name in Thai, was located 520 kilometres (322 miles) off Ilan along Taiwan's northeastern coast at 4:00pm (0800 GMT) Monday.
Packing winds of up to 126 kilometres per hour, Wipha was heading towards land at 20 kilometres per hour, the Central Weather Bureau said.
The bureau warned it could gather force, bringing heavy rain and fierce winds and urged precautions.
The typhoon's centre is forecast to be 120 km east-northeast of Ilan at 4:00 pm on Tuesday.