China is experiencing its worst heatwave in decades after rainfall hit record levels in June.

Extreme heat is also affecting Japan, while volatile weather is causing trouble for other parts of the world in what scientists say has all the hallmarks of climate change – with even more warming expected this century.

The north-east provinces of Shandong, Jilin and Liaoning saw precipitation rise to the highest levels ever recorded in June, while the national average of 112.1mm was 9.1% higher than the same month last year, the China Meteorological Administration said in a report on Tuesday.

The average temperature across the nation also hit 21.3 degrees Celsius in June, up 0.9C from the same month last year and the highest since 1961.

No relief is in sight, with higher than usual temperatures and precipitation forecast in much of the country throughout July, the administration said.

In the northern province of Henan, Xuchang hit 42.1C and Dengfeng 41.6C on June 24 for their hottest days on record, according to global extreme weather tracker Maximiliano Herrera.

China has also seen seasonal flooding in several parts of the country, causing misery for hundreds of thousands, particularly in the hard-hit south that receives the bulk of rainfall as well as typhoons that sweep in from the South China Sea.

China is not alone in experiencing higher temperatures and more volatile weather.

In Japan, authorities warned of greater-than-usual stress on the power grid and urged citizens to conserve energy.

Japanese officials announced the earliest end to the annual summer rainy season since the national meteorological agency began keeping records in 1951.

The rains usually temper summer heat, often well into July.

On Friday, the cities of Tokamachi and Tsunan set all-time heat records while several others broke monthly marks.

Large parts of the Northern Hemisphere have seen extreme heat this summer, with regions from the normally chilly Russian Arctic to the traditionally sweltering American South recording unusually high temperatures and humidity.

In the US, the National Weather Service has held 30 million Americans under some kind of heat advisory amid record-setting temperatures.

The suffering and danger to health is most intense among those without air conditioning or who work outdoors, further reinforcing the economic disparities in dealing with extreme weather trends.