Swathes of northern China sweltered in 40-degree heat on Thursday, weather data showed, as parts of Beijing and the nearby megacity of Tianjin recorded their highest temperatures for years.

Scientists say rising global temperatures -- caused largely by burning fossil fuels -- are aggravating extreme weather worldwide, and many countries in Asia have experienced deadly heatwaves and record temperatures in recent weeks.

A weather station in Tanghekou in northern Beijing logged 41.8 degrees Celsius (107 degrees Fahrenheit) early on Thursday afternoon, making it the hottest place in the country, according to local state-backed media outlet Beijing News.

Another station in the south of the city chalked up its first 40-degree day in nearly a decade, while highs of 40.6 C represented the hottest June day ever recorded in Tianjin's Xiqing district.

"It never used to get this hot in June before, but now it's so hot my hands are trembling," wrote one user on the Weibo social media platform.

"Are there three suns blazing over Beijing right now? It's hot enough to cause a breakdown," wrote another.

The scorching heat has coincided with the Dragon Boat Festival, a time when many Chinese go outside and socialise.

With temperatures in the high 30s forecast throughout the three-day public holiday, authorities have urged people to limit their time outdoors.

Beijing's weather authority issued an orange warning for extreme heat and urged people to "avoid exercising outdoors for long periods... and take effective measures to shield from the sun".

In Tianjin, where an orange alert was also in place, officials said the "general public (should) remain aware and take precautions" against heat-induced strokes.

Last week, Beijing recorded its highest temperature for mid-June, with weather officials warning the public to stay indoors as the mercury hit 39.4 C.