The typhoon is forecast to make landfall in the coastal area stretching from Hong Kong to Guangdong Province between Saturday evening and Sunday morning, China's National Meteorological Center said.
The Chinese weather forecaster maintained an orange typhoon alert on Saturday, the second-highest level in its four-tier system.
Parts of Guangdong and neighbouring Hunan and Jiangxi provinces are set to receive heavy rainfall from Saturday to Monday, it said.
When the typhoon makes landfall, it is forecast to have maximum sustained winds of 126-151 km per hour (78-94 miles per hour).
More than 20,000 people have been evacuated in Guangdong, state broadcaster CCTV said in a statement late Friday.
