Non-professional climbers are being urged to steer clear of France's Mont Blanc as extreme heat is causing more frequent rockfalls.
Mountain guides are limiting scheduled trips up the highest point in the Alps as France enters its third heatwave of the summer.
They say that access to the 4,800-metre summit is becoming too dangerous because of repeated rockfalls linked to a drought caused by extreme climate conditions.
High temperatures have narrowed and destabilised Mont Blanc's already perilous pathways, with crevasses also posing an increasing threat.
All seven routes to the mountain top remain open, but amateur climbers are being urged to stay away.
Evan Warden, a Scottish tourist who toured the base of the Aiguille summit on Sunday, said he had found "awful" conditions.
"Everywhere we walked, there were constant rockfalls and crevasses that were opening constantly," said Warden.
Norwegian couple Monica and Marten Antheun said their tour company cancelled a planned climb of Mont Blanc due to dangerous conditions.
"The guide sent us an email and the climb was cancelled because of the weather. I think the guides understand the area and the conditions. It's fine for us, we can do it later," Antheun said.
Elsewhere in Italy's Dolomites range, a 200-metre long crack appeared on the Marmolada glacier in July.
Two weeks earlier, a deadly avalanche of ice and debris there killed at least 11 people when a huge chunk of the glacier broke loose. Experts say warming temperatures are to blame.