(Bloomberg) -- The Alps are under attack from a heat wave that’s pushing freezing levels even higher than the tops of the mountain range’s glaciers.

Searing temperatures on Monday raised the freezing point above 5,000 meters (16,400 feet). Glacial peaks in the Alps are lower than that, meaning that a least temporarily they’re all entirely below freezing level, according to Italian National Research Council researcher and meteorologist Claudio Tei. 

Switzerland’s Aletsch, which tops out at just over 4,000 meters, is the largest glacier in the Alps, while Mont Blanc, on the French-Italian border, is the range’s highest peak at slightly more than 4,800 meters.

Alpine temperatures have failed to drop below zero over the past few nights, Tei said, adding that the reading at the highest point of Italy’s Monte Rosa, the 4,554-meter Capanna Margherita, never fell below 1.5 degrees C (34.7 degrees F) on Monday night.

Large swaths of normally balmy Switzerland have seen near-tropical evening temperatures in recent days, with readings at Vevey on Lake Geneva remaining above 25.4 degrees, according to weather service Meteonews. Meteorologists typically consider temperatures above 25 degrees as normal daytime readings during summer.

Highs of up to 37 degrees are expected across Switzerland on Tuesday afternoon, just days after a deadly collapse on the Fee Glacier, which sent rocks and ice tumbling below, killing a mountain climber. 

A glacial collapse in the northern Italian Alps last year killed 11 people amid higher-than-usual temperatures.

Heat waves have become more common since the late 2000s, according to Tei, who bases his findings on readings from Switzerland’s Payerne weather station dating back to 1954. 

The severe heat wave affecting northern Italy, Switzerland and France “is due to the expansion of the subtropical anticyclone,” Tei said, noting that the effect had previously been more acutely felt in central and southern Italy. 

--With assistance from Alessandro Speciale.

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