A moving band of heavy rainfall is forecast to affect large parts of China during the ongoing Labor Day holiday, a five-day break beginning Friday, with wide coverage and locally extreme conditions, according to an assessment released Friday by the country's climate monitoring and disaster response authorities.

With heavy holiday travel expected, officials warned that flood control conditions will be complex and challenging.

On Friday, the first day of the holiday, multiple government departments, including the Ministry of Emergency Management and authorities in meteorology, water resources and natural resources, held a joint consultation to assess flood risks in southern China.

They also coordinated with provinces and regions including Guangxi, Hunan, Jiangxi, Anhui, Fujian and Guizhou to plan prevention and response measures.

Authorities noted that since the start of the flood season, regions such as Jiangnan (areas south of the lower reaches of the Yangtze River) and South China have experienced several rounds of heavy rainfall, with water levels in multiple small and medium-sized rivers exceeding warning thresholds.

Local emergency authorities have been urged to strengthen preparedness for the holiday period, including reinforcing responsibilities, strengthening risk checks and improving early warning systems.

According to the Central Meteorological Observatory, a widespread rain system is expected to affect the Qinghai-Tibet Plateau, eastern parts of Northwest China, North China and southern China over the next three days.

The heaviest rainfall is forecast on Saturday in areas south of the Yangtze River, as well as the central and northern parts of South China, with some areas expected to see heavy to torrential rain, along with strong convective weather.

Affected by cold air and precipitation, temperatures in both northern and southern China are expected to drop, with daytime highs falling below seasonal averages.

From Friday to Sunday, temperatures in Northwest, North and Northeast China are expected to fluctuate and decline. Taiyuan in Shanxi province and Beijing are forecast to drop to around 20 C on Saturday, while the high of Harbin in Heilongjiang province will fall to about 15 C, a sharp contrast to the warm weather before the Labor Day holiday.

In southern China, temperatures will also decline as rainfall develops. Major cities such as Shanghai, Nanjing in Jiangsu, Wuhan in Hubei and Nanchang in Jiangxi are expected to see highs just above 20 C, below the average for this time of year.