BEIJING - A yellow alert has been issued ahead of Typhoon Nari, the National Marine Environmental Forecasting Center said on Friday.

Nari, which will be the 25th typhoon to hit China this year, is expected in the middle and eastern parts of the South China Sea on Saturday noon, the center said.

From Friday noon to Saturday midday, there will six-meter high waves in the eastern part of the South China Sea. Waves of up to three meters high are expected in the southern part of the East China Sea, the Taiwan Strait and the northeastern part of the South China Sea.

The center said Huangyan Island, in the mid-east region of the South China Sea, will be heavily affected by the typhoon. It warned China Coast Guard vessels that are patrolling the waters around the island to take precautions.

The center also warned fishing boats not to sail in severe weather conditions in the South China Sea and the Beibuwan Gulf off the coast of south China's Guangxi Zhuang Autonomous Region.

China has a four-tier color-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue.