BEIJING -- China's National Marine Environmental Forecasting Center (NMEFC) upgraded its warning for ocean waves triggered by Typhoon Meranti to "red" on Wednesday, the highest alert on a four-color warning system.

Gales and waves up to 12-meters high have been observed off the eastern coast of Taiwan, as the 14th typhoon this year moves westward and is expected to hit the coast of Fujian, Zhejiang and Guangdong provinces on Wednesday and Thursday.

The typhoon is expected to make landfall in Fujian and Guangdong on Thursday and the State Oceanic Administration has initiated a class-II emergency response, the second highest level.

Ships have been ordered to return to harbor and residents to stay indoors, according to the NMEFC. It's also been advised that dams should be reinforced.

Li Mei, a meteorologist in eastern China's Fujian, said that Meranti is among the strongest typhoon to hit China in recent years.

Schools and kindergartens in coastal cities of Fuzhou, Xiamen, Zhangzhou, Quanzhou and Putian were closed Wednesday.

"The typhoon will bring gales and heavy rains when it makes landfall," Li said. "Parents are advised to keep the children indoors and stay away from unsafe houses and advertising boards."

Passenger liners on eight routes between Fujian and Taiwan were canceled on Wednesday, as were at least 175 flights in and out of Fujian.

According to Chen Jianping, an official with Guangzhou Railway Group, services of many passenger trains have been stopped. Passengers can have their tickets refunded at railway stations.

More than 4,000 workers are patrolling railways to monitor potential risks, Chen said.

Under China's four-tier severe weather warning system, red is the most serious, followed by orange, yellow and blue.