MétéoSuisse’s 2025/2026 winter review reveals unusually low snow depths and major precipitation deficits across the central and eastern Alps. But the real story for infrastructure operators is bigger than snow — it is about how a changing mountain environment reshapes geohazard risk, and why real-time geohazard monitoring matters.

The 2025/2026 Alpine Winter Was Not Just a Snow Story

MétéoSuisse has published its review of the 2025/2026 winter season in the central and eastern Alps. At first glance, this may appear to be a report about snow conditions. In reality, it raises a much broader question for anyone responsible for Alpine infrastructure: how do roads, railways, tunnel portals, slopes and protective structures remain resilient when the mountain environment around them is changing?

The report describes frequent temperature inversions during the winter season. In simple terms, this meant mild and sunny conditions at higher altitudes, while colder air remained trapped beneath fog and stratus in lower-lying areas. MétéoSuisse notes that, because of these repeated inversion situations, temperature deviations from the long-term average were greater at higher altitude, particularly in November and December. [1]

The snow figures are also striking. Across the Alpine regions of Germany, Austria and Switzerland, average snow depths during the 2025/2026 winter season were among the five lowest recorded since 1991. The northern Alps experienced their second-driest winter since 1991, while the southern Alps recorded their driest winter in the same period. [1]

Importantly, MétéoSuisse makes a clear distinction: the lack of high-altitude snow was driven primarily by a precipitation deficit, rather than temperature alone. [1] That detail matters, because it prevents the story from becoming too simplistic. This was not just “a warm winter”. It was a winter shaped by mild high-altitude conditions, persistent weather patterns, low precipitation and unusually low snow depths — and for infrastructure operators, that combination deserves attention.

One Dry Winter Does Not Prove More Landslides

It is important to be precise. The 2025/2026 MétéoSuisse report does not say that this single winter directly caused more rockfalls, landslides or debris flows. Nor should anyone claim that low snow depths automatically lead to more slope failures.

Mountain hazards are more complex than that. Rockfalls, landslides and debris flows are shaped by geology, slope angle, temperature, water, freeze-thaw behaviour, permafrost, vegetation, snow, rainfall and time. A dry winter may reduce some types of immediate water-related instability, but it may also leave the landscape exposed in other ways. Later heavy rainfall, rapid snowmelt, thawing ground or repeated freeze-thaw cycles can all affect how slopes behave.

So the point is not that one MétéoSuisse winter report explains every future geohazard. The point is that it forms part of a wider pattern: Alpine climate conditions are changing, and the assumptions that infrastructure operators have traditionally relied on are becoming less stable. MétéoSuisse states that the Alpine region is more strongly affected by the consequences of the human-caused greenhouse effect than many other regions or natural areas, and that the effects of climate change are clearly visible in this highly sensitive environment. [1]

That is the context in which the 2025/2026 winter should be read — not as an isolated snow report, but as part of a changing risk environment.

Why Changing Alpine Conditions Matter for Geohazards

The European Alps have always been exposed to rockfall, landslide and debris-flow risk. What is changing is the background environment in which those hazards occur.

A major review of observed Alpine mass movements found that anthropogenic climate change is altering high mountain environments, including the frequency, behaviour, location and magnitude of some Alpine mass movements. The review examined research from across the European Alps, including rockfalls, rock avalanches, debris flows, ice avalanches and snow avalanches. [2] One of the clearest climate-controlled trends identified was an increase in rockfall frequency in high-Alpine areas linked to higher temperatures. The same review also found a clear increase in precipitation capable of triggering debris flows, although this has not translated into uniform increases in debris-flow activity everywhere. [2]

That distinction is essential. This is not a neat story where every hazard increases in the same way, everywhere, all at once. It is more complicated than that. Some areas may experience greater rockfall activity because of warming rock faces, glacier retreat or permafrost degradation. Other areas may become more exposed to intense rainfall events. Some places may see changes in hazard seasonality rather than simply more frequent events.

For infrastructure operators, the practical message is clear: historic assumptions about where, when and how geohazard events occur may no longer be enough.

Permafrost, Glaciers and Slope Instability

One of the most important climate-related concerns in high mountain environments is permafrost. Permafrost is ground that remains at or below 0 °C for at least two consecutive years. In Alpine terrain, ice within fractures and loose material can help hold slopes together. When that frozen ground warms and thaws, the stability of rock faces and debris-covered slopes can change.

WSL and SLF state that climate change causes permafrost to warm and thaw, and that Alpine hazards increase as ground thaws, raising the potential for slope instability. They also report that permafrost in the Alps is warming by around 1 °C per decade. [3] This has direct consequences for infrastructure. WSL and SLF specifically identify a wide range of assets that can be at risk if permafrost thaws:

• Mountain railways and railway tracks
• Cable car stations, masts and shelters
• Water pipelines and avalanche barriers
• Telecommunications facilities and snow sheds

Rock glaciers are also moving faster. WSL and SLF report that rock glaciers are now moving downhill two to three times faster than they were 20 years ago. As the active layer of permafrost becomes thicker, more material can be released from steep fronts, increasing the potential for rockfall or debris flows. [3]

This is where climate change becomes an infrastructure issue. It is not only about temperature records. It is about what happens when the frozen, wet, fractured and unstable parts of the mountain begin to behave differently.

Heavy Rainfall and Debris-Flow Risk

Water remains one of the most important triggers for landslides and debris flows. WSL explains that landslides can occur when soils on slopes become saturated with water during heavy rainfall, and that these events can endanger buildings, roads and railway tracks. WSL also notes that melting glaciers and thawing permafrost can release rocks and boulders from their icy grip, while heavier rainfall could make hillslope debris flows more frequent. [4]

This means infrastructure managers face a difficult combination. A winter may be unusually dry, yet the following season may bring intense rainfall. A slope may look stable during inspection, and then a short, high-intensity storm may change the risk picture very quickly.

This is why climate resilience cannot depend only on seasonal averages or historic patterns. It also requires real-time information from the infrastructure and slopes themselves.

It Would Be Remiss Not to Mention ImpactSentinel™

At this point, it would be remiss of us not to mention ImpactSentinel™ — This is exactly the type of risk environment our systems are built for.

INGLAS is a specialist provider of real-time rockfall, landslide and slope-monitoring alarm systems. ImpactSentinel™ is designed for locations where infrastructure is exposed to physical geohazard risk: railway corridors, mountain roads, tunnel portals, rockfall barriers, protective fences, steep slopes, targeted rocks, retaining structures and vulnerable assets in remote terrain. [5]

Climate and weather data help explain how the risk environment is changing. ImpactSentinel™ provides the operational layer when a physical incident actually occurs. That distinction matters. ImpactSentinel™ is not a climate model, and it does not claim to predict every rockfall or landslide before it happens. Its role is more practical and, in many cases, more immediate.

When installed in an area to be monitored, ImpactSentinel™ sensors can detect impact, vibration, movement, tilt and pull-out conditions. When a configured alarm threshold is exceeded, the system can rapidly notify the relevant operators, infrastructure managers or authorities. [5] That may be a smaller impact requiring inspection, or a larger event requiring immediate closure, intervention or emergency response. Either way, the value is the same: the event is no longer hidden until the next visual inspection, public report or scheduled maintenance visit.

From Passive Protection to Real-Time Geohazard Monitoring

Many rockfall barriers, fences and protective structures are designed to absorb or redirect hazardous material. But a passive structure does not automatically tell an operator what has happened. A small rockfall may strike a low-energy barrier, a slope may shift, a monitored wall may tilt, a targeted rock may move, or a protective fence may be damaged but still appear broadly intact from a distance.

Without real-time monitoring, these events can remain unknown until someone physically inspects the site. In remote Alpine terrain, that may not happen immediately. It may not happen safely. It may not happen before the next weather event adds further stress. This is the gap ImpactSentinel™ is designed to close.

The system can support monitoring of smaller incidents as well as major events, provided the movement, impact, vibration, tilt or pull-out condition exceeds the configured threshold. [5] This matters because smaller events are not always insignificant. They can:

• Indicate increased slope activity
• Weaken protective structures
• Inform maintenance planning
• Help operators understand how a site is behaving over time

A major incident may demand immediate action. A smaller incident may demand inspection. Both are more useful when they are known quickly.

Why Real-Time Alarming Matters for Railways, Roads and Tunnel Portals

Alpine infrastructure often operates in narrow corridors where there is little room for error. Railway lines pass below rock faces, roads run beneath unstable slopes, and tunnel portals sit at the point where vehicles or trains move between protected and exposed terrain. Protective structures are often installed in places that are difficult to access and expensive to inspect.

In these locations, speed of awareness matters. A real-time alarm can support faster decision-making, helping operators dispatch inspection teams, check barriers, review visual confirmation, close exposed infrastructure or activate predefined safety protocols. ImpactSentinel™ is designed to communicate alarms within seconds, depending on the site configuration and communication architecture. [5]

That speed is important because the real operational question is rarely theoretical:

It is not simply “Could this slope be dangerous?” It is “Has something just happened?” And if something has happened: “Who needs to know now?”

A More Honest Way to Talk About Climate and Monitoring

There is a temptation in climate-related marketing to overstate the case. Every storm becomes a warning, every rockfall becomes a climate-change event, and every report becomes a sales opportunity. That is not the right approach.

The 2025/2026 MétéoSuisse winter report should be treated carefully. It shows unusual and important Alpine climate conditions, but it does not, by itself, prove a direct increase in rockfall or landslide events during that winter. What it does do is contribute to a serious and evidence-based conversation.

The Alpine environment is changing. Scientific research is identifying climate-linked changes in high-Alpine rockfall, debris-flow-triggering precipitation and other mass-movement processes. Permafrost is warming, glaciers are retreating, and heavy rainfall remains a critical trigger for slope instability. Infrastructure operators need systems that help them understand not only the changing background risk, but also the moment when that risk becomes a physical incident.

This is where real-time geohazard monitoring belongs. It is not a replacement for:

• Climate science
• Geotechnical expertise
• Protective structures

Instead, it acts as a practical operational layer between the mountain and the people responsible for keeping critical infrastructure safe.

Conclusion: Resilience Depends on Knowing What Has Happened

The 2025/2026 winter season in the central and eastern Alps was marked by frequent temperature inversions, unusually low snow depths and significant precipitation deficits. Those facts matter — not because one dry winter explains every future hazard, but because they sit within a wider climate context that is already affecting the Alpine environment.

For railways, roads, tunnel portals, slopes and protective structures, resilience will depend on more than long-term climate awareness. It will also depend on real-time operational awareness.

Changing Alpine winters are not only a snow story. They are an infrastructure resilience story. And for INGLAS, they are exactly the kind of scenario where real-time geohazard monitoring and alarming has a clear role to play.

Sources

[1] MétéoSuisse — “La saison hivernale 2025/2026 dans les Alpes centrales et orientales”
https://www.meteosuisse.admin.ch/portrait/meteosuisse-blog/fr/2026/06/la-saison-hivernale-2025-2026-dans-les-alpes-centrales-et-orientales.html

[2] Jacquemart, M., Weber, S., Chiarle, M., Chmiel, M., Cicoira, A., Corona, C., Eckert, N., Gaume, J., Giacona, F., Hirschberg, J., Kaitna, R., Magnin, F., Mayer, S., Moos, C., Stoffel, M., and van Herwijnen, A. — “Detecting the impact of climate change on alpine mass movements in observational records from the European Alps”
https://meetingorganizer.copernicus.org/EGU25/EGU25-16339.html

[3] Swiss Federal Institute for Forest, Snow and Landscape Research WSL / SLF — “Climate change and … permafrost”
https://www.wsl.ch/en/news/climate-change-and-permafrost/

[4] Swiss Federal Institute for Forest, Snow and Landscape Research WSL — “Slopes in motion: rockfalls and landslides”
https://www.wsl.ch/en/natural-hazards/rockfalls-and-landslides/

[5] INGLAS GmbH & Co. KG — ImpactSentinel™ real-time rockfall and geohazard monitoring information
https://inglas.org/rockfall-landslide-detection/