Our blog:
Massive snowfalls in the Alps during this week's record-breaking April storm!
by Fraser Wilkin, 19 April 2025
The storm that hit the western Alps on 16 and 17 April 2025 will go down as one of, if not THE most significant April snowstorms in living memory.
Exceptional as this storm was, snowfall totals were reasonably well forecast, at altitude at least, so we knew several days in advance that the Alps were going to be in for something special. However, what caught everyone by surprise, contributing to the chaos it caused in the Alps, was the intensity of snowfall at lower altitudes.
Arc 1600 covered with new snow on the morning of Thursday 17th April 2025 – Photo: Nico080 via Infoclimat.fr
In the Alps, the areas most impacted by this storm were the eastern French Alps (especially the Tarentaise and Haute-Maurienne regions), the western Italian Alps (especially the Piedmonte and eastern Aosta) and the western Swiss Alps.
Home to most of France’s highest ski resorts (many of which remain open), the Tarentaise grabbed most of the headlines, with Val d’Isère, Tignes and La Rosière all clocked just over 1m of fresh snow at resort level. Nearly all of this fell within a period of 24hrs or less between Wednesday afternoon and Thursday lunchtime. To the best of our knowledge this is an unprecedented snowfall total for April and would have been even greater had the precipitation not initially fallen as rain.
Huge snowfalls in La Rosière on Thursday 17th April 2025 – Photo: HauteTarentaise7 via Infoclimat.fr
1 metre of snow fell in 24-hours in Val d’Isère overnight on 16th and 17th April 2025 – Photo: radiovaldisere.com
Higher up there was obviously even more snow, with around 160cm on the glacier in Tignes, and reports of over 200cm in 48-hours on the Pisaillas glacier above Val d’Isère between Tuesday and Thursday!
Lower down, Bourg Saint Maurice saw 38cm – its second biggest April snowfall on record – while Modane saw 55cm – its biggest April snowfall on record. These figures are particularly surprising given that freezing levels remained close to 2000m for much of the storm.
Chaos on the motorway near Modane in the Savoie, France on Thursday 17th April 2025
So why did so much snow fall to such low levels in the Alps?
The answer is ‘Evaporative Cooling’ or what the French call ‘Neige par Isothermie’. For this to take place, the two conditions required are: (1) intense precipitation, and (2) little (if any) wind. Both of these were present during the middle of this April storm.
Simply explained, when falling snowflakes turn into raindrops, the melting process requires energy. This is drawn from the heat of their surroundings, cooling the column of air that the snowflakes are falling through. If this process continues, the column of cooled air is dragged ever downwards towards the ground.
This ‘evaporative cooling’ can allow rain to turn to snow even if the ambient temperature of the airmass is relatively high. In a typical storm, the rain/snow limit would be perhaps 200-300m below the general freezing level. However, overnight on Wednesday and on Thursday morning the Alps saw heavy snow to as low as 700m despite general freezing levels being close to 2000m!
The French Alps were certainly not alone in taking a hit from this huge April storm. The western Swiss Alps were also badly affected. While snowfall totals of 53cm in 24-hours (at resort level) in both Adelboden and Crans Montana, and 75cm at Les Ruinettes above Verbier, may not sound quite as crazy as the totals seen in the Tarentaise in France, they still broke all-time records for April.
Massive snowfalls even at resort level in Verbier on Thursday 17th April 2025 – Photo: 24hrs.ch
Furthermore, the snow that fell was very wet, meaning that it stuck to everything: bringing down trees and powerlines, and crippling transport infrastructure. Zermatt, which saw 55cm of wet snow at resort level (and much more higher up), for example, was cut off for a time due to the risk of avalanche above both its access road and railway.
The western Italian Alps may have grabbed fewer snow-related headlines, probably due to fewer ski resorts in the region still being open, but were also in the firing line from this April storm. There have been reports of 1.5 to 2 metres of snow falling in 48-hours in some high border areas of the Piedmonte, and lots of flooding issues lower down.
Needless to say, once things have settled down – which they will quite quickly – snow coverage is now very impressive at altitude in the western Alps for mid- to late April. There are a few notes of caution though!
Just because there is a lot of new snow, this doesn’t mean that it is of good ‘quality’ or that there is a lot of powder around (other than at very high altitude). This storm delivered very 'heavy' and 'wet' snow from the outset, and the strength of the sun means that the benefits of any fresh snow can be very short-lived at this time of year.
Spring conditions therefore remain the order of the day across the Alps, and the off-piste remains highly dangerous due to the risk of avalanche.
If you enjoy reading our updates - please feel free to support us:
Print