The twentieth edition of the report describes the evolution of the 2024-2025 snow season. It was a season characterised by below-average snow cover in the south-eastern sectors and close-to-average conditions in the north-western sector above 2,000 m, by temperatures higher than the historical average though without the extremely warm periods seen the previous winter and by the heavy snowfalls of 16 and 17 April, when numerous spontaneous avalanches were observed.
Snow cover remained in line with the historical average in the north-western sector throughout the season, while it was scarce over the rest of the region until March. Between 16 and 17 April, it returned to levels equal to or close to the historical average above 2,000 m across the entire region, thanks to an extreme precipitation event.
From December to March, snowpack instability was mainly due to numerous wind events and the presence of persistent weak layers. From the beginning of April, however, wet snow became the main factor of instability, together with the fresh snow accumulated during the heavy mid-April snowfalls.
The most critical period of the season for human-triggered avalanches was March, particularly the second half of the month: during this interval, 8 of the 12 accidents recorded throughout the season occurred. With regard to spontaneous avalanches, three significant avalanche cycles were observed: one a few days before Christmas, one at the end of January, both in the western sector of the region, and the third, the most important, coinciding with the extreme precipitation event of mid-April.
During this extreme event, the valleys most affected were those of Gran Paradiso, the Lys Valley, Valpelline and Val Ferret. Numerous avalanches were observed, some of which approached refuges and alpine pastures dangerously, and in some cases interrupted road traffic. Local avalanche commissions were constantly engaged in monitoring the snow and weather conditions and in controlling road sections potentially at risk.
Overall, 532 avalanches were recorded during the season: 74 never documented before, 71 larger than those known in the past, and 12 avalanche accidents occurring in the Aosta Valley.
