The southern Chinese provinces of Hainan, Guangdong and Fujian are preparing for Chanchu, the first tropical storm of the year and probably the strongest ever to hit south China in May, local meteorologists say.

The storm intensified into a typhoon on Saturday and its center was located at 14 degrees north latitude and 115.4 degrees east longitude at 2:00 a.m. Monday, 870 kilometers from the southern island province of Hainan, the provincial meteorological bureau in Hainan said.

It said the outer rim of the typhoon has cooled down the island province, lowering its maximum daytime temperature to between 27 and 29 degrees Celsius Monday from 36 degrees last week.

The typhoon is moving northwestward at 10 to 15 km per hour and will be landing in the central eastern parts of Guangdong Province on Wednesday.

Affected by the typhoon, most parts of Hainan, Guangdong and Fujian provinces will be overcast or rainy in the coming three days, and some counties in Fujian Province are in for rainstorm.

Nearly 1,000 fishing boats have been called back as high wind is predicted on South China Sea starting on Monday afternoon.

Chanchu, whose name means "pearl", formed in the northwestern Pacific, about 550 km to the east of Mindanao island in the Philippines on May 9. It hit central Philippines on Saturday, killing at least 32 people and leaving more than 1,000 others homeless.