Several regions have been given high fire danger ratings as authorities warned high winds could whip up bushfires and urged residents to minimise fire risks at their houses.

The heatwave has also elevated the risks of fires with several regions given 'high' fire danger ratings, and authorities urging residents to prepare for bushfires.

This year's previous high was 32.6 C, reached on Thursday.

Temperatures are expected to rise to between 40 and 42 Celsius in the southern departments of Ardeche, Drome, Vaucluse and Gard, reports say.

Sweltering temperatures have affected swathes of the planet, with heat records registered from Death Valley in the US state of California to a northwest China township as Canada and southern Europe battle wildfires.

Hundreds of those attending the jamboree of about 40,000 scouts from 155 countries have been laid low by temperatures of 33 Celsius, and some troops have pulled out.

Hundreds of participants have already fallen ill due to the searing temperatures, prompting complaints from parents over the safety of their children.

South Korea raised the heat warning level in its four-tier system to the highest on Tuesday, the first time since 2019.

Temperatures are expected to be 39 C in Tehran on Wednesday.

The number of 'hotspots' recorded between July 17 and July 23 surged to 12,701 from 6,082, reports say.

Facekinis, or full face masks with holes for the wearer's eyes and nose, sleeves to cover arms, as well as wide brimmed hats and lightweight jackets made out of UV-resistant fabric have become especially popular.

People with cardiovascular and respiratory diseases and diabetes, as well as pregnant women, children and homeless people, are seen as the most vulnerable to heatwaves.