China's national observatory on Thursday renewed its red alert for Typhoon Saola, which is expected to bring gales and heavy rains to the country's eastern and southern coastal regions.

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

Saola, the ninth typhoon hitting China this year, was sighted over the water approximately 330 kilometers southeast of Huilai County in south China's Guangdong Province around 5 a.m. Thursday, and is expected to move northwest at a speed of 10 kilometers per hour with gradually decreasing strength, according to the National Meteorological Center.

It will make landfall anywhere along the coast from Huilai to Hong Kong on Friday afternoon or Friday night, or it will proceed southwest and pass across the waters of eastern Guangdong without reaching landfall, according to the center.

Gales with a maximum wind force of more than grade 17 will hit some areas around the Bashi Channel, the Taiwan Straits, the South China Sea, and the coastal areas of China's Fujian and Guangdong provinces and the Taiwan region from 8 a.m. Thursday to 8 a.m. Friday, the center said.

China categorizes wind speeds from 0 to 17. A Category 17 typhoon is a super typhoon with a maximum speed of 60 meters per second.

Parts of Fujian, Guangdong and Taiwan may see severe rain during this period, with some locations receiving 100 to 220 millimeters of rain, according to the center.

The meteorological center has issued an advice recommending the prompt relocation of people residing in vulnerable housing and suspending all outdoor gatherings and activities.

Additionally, it has called for emergency typhoon preparations and safeguarding against potential geological catastrophes.

(With input from Xinhua)