Zhengzou, July 18 : Central China's Henan, one of the country's most populous provinces, is enduring its hottest July since 1961 as a prolonged heatwave grips much of the region, local meteorological authorities said Friday.

Since the start of July, Henan has recorded an average of 10.8 high-temperature days, defined as days with temperatures reaching 35 degrees Celsius or above, 7.8 days more than the seasonal average. Seven weather stations reported their longest-ever streaks of such days in July.

The province's average temperature so far this month has been 3.8 degrees Celsius above the historical norm, with daily highs climbing to 40 degrees Celsius or more in 131 counties and districts between July 13 and 16, Xinhua news agency reported.

Meteorologists attributed the extreme heat to a subtropical high-pressure system, which traps heat and causes hot, dry weather.

The heatwave is expected to ease starting July 21, with widespread rainfall forecast across the province.

China's national observatory renewed a yellow alert on Friday, warning of high temperatures in some regions of the country. Parts of southwest China's Chongqing Municipality, Sichuan Province, and Xinjiang Uygur Autonomous Region in the northwest are expected to see temperatures exceed 40 degrees Celsius.

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

On July 14, a prolonged heat wave was forecast to affect multiple regions across China from July 14 to 22, with some areas expected to approach or exceed historical temperature records, according to China's National Meteorological Centre (NMC).

"With the subtropical high-pressure system extending further north, heatwave conditions have intensified over recent days in North China and the Yellow-Huaihe river basin," said Zhang Bo, a forecaster with NMC. "The areas seeing daily maximum temperatures above 37 degrees Celsius are expanding, and the humid heat is becoming increasingly pronounced."

/IANS