Typhoon Kalmaegi, which was 180 km (112 miles) southeast of Taiwan at 0030 GMT, will reach the northeast coast at about 1500 GMT with sustained winds of 101 kph (63 mph) and gusts of 126 kph, the island's Central Weather Bureau said.
The bureau issued wind and rain warnings for greater Taipei, the northern port city of Keelung and three other counties. It also warned boats off the south and east coasts.
"Rain will strengthen from Thursday morning in typhoon-affected areas," the bureau said in a statement on its website, www.cwb.gov.tw. "In eastern Taiwan, wind-blown waves will get quite large."
Storm-tracker Tropical Storm Risk said Kalmaegi would grow to become a category 1 typhoon, the lowest on a 1-5 scale. It issued a red alert for Taipei.
The storm will proceed to China, hitting the coast of Zhejiang province as early as Friday, Tropical Storm Risk said on its website, www.tropicalstormrisk.com.
Typhoons regularly reach China, Taiwan, the Philippines and Japan from August until the end of the year, gathering strength from the warm waters of the Pacific or the South China Sea before weakening over land.
Krosa, the last typhoon to hit Taiwan, kept people indoors as work and classes were cancelled. Three people were injured in the early October storm.
