December marks the return of CIMA Research Foundation’s monthly snow water resource monitoring. While the mountains have finally seen their first snowfalls, the season begins with a 1 -63% deficit in snow water equivalent.
The meteorological winter has officially arrived, but it starts with uncertainty for our mountains. After weeks of waiting, the first snowfalls have brought relief to some regions while leaving others still in deficit. CIMA Research Foundation remains committed to tracking this crucial reality, offering an updated overview of snow conditions in the Italian mountains, also accessible through a dedicated webpage. As we know all too well, today’s snow is tomorrow’s water: monitoring snow data throughout the winter is critical for estimating the water resources that will be available in the spring and summer months.
The first assessment of the 2024/25 season provides an insightful perspective on how climatic conditions influence snow accumulation in the early stages of the season. As we will see, temperature and precipitation trends have had a clear impact on snowpack development during the initial weeks, but the overall picture remains dynamic and evolving. The season is still in its early stages, and climatic variables could offer opportunities for recovery in the coming weeks.
A cold but dry November
Snow accumulation is the result of a complex balance between temperature and precipitation. November 2024 recorded temperatures generally below the average of the last decade, theoretically favorable conditions for snow accumulation. However, the month was also marked by a significant lack of precipitation across most of Italy, delaying the onset of the snow season, particularly in the Alps.
“This is a clear example of what we expect from the impacts of climate change, which makes winters milder and often drier and/or more unpredictable,” explains Francesco Avanzi, researcher at CIMA Research Foundation. “November is typically one of the wettest months in our Mediterranean-temperate climate. This year, the low precipitation levels have clearly limited early-season snow accumulation, though there is still time for recovery.”
The data highlights these dynamics. The lack of precipitation particularly affected the Alps, where the snow season had virtually not begun until last week. The result? A marked snow water deficit, with the Po basin currently experiencing a -67% deficit.
Regional differences: Struggles in the Alps, recovery in the Apennines
Snow monitoring in Italy is never uniform, and this first update confirms it. The Alps, which form the backbone of Italy’s snow water resources, are facing challenges. In the Po and Adige basins, late-November snowfalls slightly improved the situation but not enough to make up for the delay accumulated earlier.
The Apennines present a different picture. Abundant snowfalls since late November have brought relief. In the Tiber basin, for instance, snow levels are consistent with the seasonal average, while above-average conditions have been recorded in the Tuscan-Emilian Apennines and even in Sicily.
These results underscore the heterogeneity of the Italian landscape and the importance of monitoring tailored to local specificities. As Avanzi highlights: “The Alps remain the primary reservoir of snow water resources in Italy, but the role of the Apennines should not be underestimated, especially in seasons characterized by strong climatic discontinuities.”
What lies ahead in the coming months?
The beginning of the season is only a small part of the story—a preliminary phase in a complex, dynamic process influenced by numerous climatic and meteorological factors, lasting at least until April or May. To understand the potential development of the snow season, it is crucial to analyze medium- and long-term projections, bearing in mind their inherent uncertainties.
The ECMWF2 model projections for the January–March 2025 period indicate a positive temperature anomaly, with values above the climatic average across much of Europe, particularly in the central Alpine arc. This could reduce snow accumulation and accelerate early melting processes, especially in the late season. However, it is important to note that atmospheric variability can lead to significant snow events even during periods with generally higher temperatures over a trimester.
Meanwhile, precipitation projections suggest conditions close to the historical climatology—an encouraging sign for potential snow accumulation. Starting from the premise that these forecasts are highly uncertain, the balance between above-average temperatures and normal precipitation opens diverse scenarios depending on the timing and intensity of meteorological events. For example, abundant precipitation during temporary cooling episodes could result in a significant recovery of snow resources, particularly in the Alps. Even in this scenario, the key issue will be whether the snow remains accumulated in the mountains or melts prematurely during increasingly frequent winter heatwaves.
As Avanzi concludes: “Seasonal forecasts provide a general indication, but reality can deliver sudden surprises. Continuously monitoring the data is essential to understand how the season will unfold. The next update is scheduled for January, when new data will provide the next chapter of this long winter marathon.”
- Snow Water Equivalent (SWE): find out the scientific definition here. ↩︎
- The European Centre for Medium-Range Weather Forecasts is concerned with providing operational forecasts that aim to show how the weather is most likely to evolve. To this end, the Centre produces a set of forecasts. Individually, they are comprehensive descriptions of weather evolution. Taken together, they indicate the probability of a range of future weather scenarios. See https://www.ecmwf.int/en/forecasts ↩︎