China endured its hottest summer on record this year, with average national temperatures reaching unprecedented levels from June to August, according to the National Climate Center.

The national average temperature for the past three months hit 22.31 C, the highest since record-keeping began. Northwestern and central regions such as the Xinjiang Uygur autonomous region and provinces of Shaanxi, Henan, Shanxi and Shandong registered their hottest summers ever, while provinces including Jiangsu, Zhejiang, Hebei and Sichuan recorded their second-hottest season.

August proved especially punishing in the south, where major cities broke records for sustained heat. Shanghai's Xujiahui recorded 27 days of temperatures above 35 C, while Hangzhou logged 29 such days, both setting new highs for August.

Meteorologists attributed the sweltering conditions to unusually strong subtropical and continental high-pressure systems. "These systems create sinking air, little rainfall and weak winds, allowing more solar radiation to heat the surface," said Ouyang Yi, an analyst with weather.com.

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As September begins, the heat has eased somewhat but has not fully retreated. On Monday, Hangzhou in Zhejiang province and Shanghai again reached 35 C, extending record-breaking streaks.

By Sept 5, high temperatures are expected across the Sichuan Basin and much of the Yangtze River Delta, affecting cities such as Shanghai, Hangzhou, Hefei in Anhui province and Wuhan in Hubei province.

Despite temporary breaks, high humidity will continue to exacerbate the sweltering conditions. People in southern China are urged to reduce outdoor activity during peak hours, according to weather.com.