A 500,000 cubic metre chunk of the Planpincieux Glacier is on the verge of breaking away because of high temperatures.
An Italian resort in the Alps remained on high alert on Friday over fears a massive glacier could collapse due to high temperatures.
The municipality of Courmayeur in the Valley of Aosta ordered dozen of residents and tourists to evacuate from a large exclusion zone on Wednesday because of a high risk of avalanche. Several roads have been closed and pedestrian access is strictly prohibited.
The area is popular with hikers in the summer.
Local officials said in an order decree that a chunk of ice of approximately 500,000 cubic metres is on the verge of breaking away from the Planpincieux Glacier.
The glacier is "the size of Milan cathedral or a football pitch covered in ice 80 metres (260 feet) thick" according to an official. It could break free of its perch about 2,600 to 2,800 metres above sea level.
The decree, which warns of legal repercussions against those who flout it, is to be in vigour "for at least three days".
The mercury in Courmayeur, which is located 2,000 metres above sea level, was expected to climb to 17° this afternoon and 19°C on Friday afternoon. Temperatures of 4°C and 5°C degrees were meanwhile forecast at altitudes of 4,000 m.
France, which shares the Mont Blanc with Italy, is to experience a heatwave in the coming days with temperatures as high as 39°C expected on Saturday in the east of the country.
It comes after the country recorded its driest July in more than 60 years, with the mercury 0.9°C higher than average.
According to the Research Centre for Alpine Ecosystems (CREA), over the course of the 20th century, temperatures in the European Alps have risen by 2°C — higher than the French average of +1.4°C and double the increase recorded in the northern hemisphere.
In September and October 2019, a 250,000 cubic metre chunk of the Planpincieux Glacier had already threatened to collapse.