Mont-Blanc
Avalanche Bulletin for Mont-Blanc — covering resorts: Chamonix (Brévent-Flégère), Chamonix (Grands Montets / Argentière), Chamonix (Le Tour-Balme), Vallorcine, Les Houches, Megève, Saint-Gervais-les-Bains, Saint-Nicolas-de-Véroce, Combloux, Les Contamines-Montjoie, La Poya (Chamonix), Les Houches (Chamonix), Les Contamines, Megève/Saint-Gervais, Le Tourchet (Chamonix), Brévent/Flégère (Chamonix), Balme - Vallorcine, Les Grands Montets, Les Chosalets (Chamonix), Les Planards (Chamonix), Aiguille du Midi (Chamonix), Vormaine, Les Houches - Saint-Gervais
Source : Météo-France
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Source: Météo-France
Avalanche risk assessment bulletin
(valid outside of marked and open slopes)
MASSIF: Mont-Blanc
written on Sunday 24 May 2026 at 4 pm.
Risk assessment for Monday 25 May 2026
The moistening of the snow cover continues.
Risk indices: 5 very high - 4 high - 3 considerable - 2 moderate - 1 low -- In black: the most dangerous slopes
Above 2800m moderate risk level, lower down low level.
Naturally triggered avalanche: Small releases in the sun.
Skier-triggered release: Wet snow slides under skis as the warming progresses.
Stability of the snow cover until Monday 25 May evening
Typical avalanche situation:Wet snow
Skier-triggered release: * Above 2800 m: wet snow sluffs under skis, more and more easily as solar warming progresses. More frequent releases in a wide north sector, where wetting is still low but gradually gaining depth. Size 1 (small) to 2 (medium) Naturally triggered avalanche: * Above 2800 m: on slopes in a wide north sector warmed by the sun: rare point-release avalanches as solar radiation increases. Size 1 (small).
Snow quality
Snow conditions:
For the season, snow conditions are below average below 2800 m and good above. Snow is present in quantity only above 2000/2200 m in the North and 2300/2400 m in the South.
Snow quality this Monday:
* Below 2300 m: firn patches remain. Refreezing is moderate in the morning.
* Between 2300 and 3200m: spring snow cover: frozen in the morning then wet in the afternoon resting on a hard base. Significant foot penetration.
* Above 3500 m: Still a little cold, powdery and dense snow on north faces (in the steepest North-facing slopes, the limit is lower, around 3200m). Wind-affected snow near ridges and summits. On South-facing slopes, a thin non-load-bearing crust in the morning that quickly softens in the sun.
Weather overview for Monday 25 May
| night | morning | afternoon | evening | |
|---|---|---|---|---|
| Grand soleil toute la journée avec une grande chaleur presque estivale. Quelques cumulus sur le relief l'après-midi. | ||||
| Rain-Snow | - | - | - | - |
| Iso 0°C | 4000 m | 4000 m | 4100 m | 4200 m |
| Wind 2000 m | 5 km/h | 5 km/h | 5 km/h | 5 km/h |
| Wind 4000 m | 10 km/h | 10 km/h | 10 km/h | 5 km/h |
Off-piste snow depth
Precipitation at 1800 m
Trend for Tuesday 26 May
Risk index moderate
Steady risk. Deep wetting of the snow cover is progressing significantly at altitude given the temperatures. The stabilization of the snow cover continues.
Snow-weather conditions for the last 7 days
Last 7 days
| Mon. 18/05 | Tue. 19/05 | Wed. 20/05 | Thu. 21/05 | Fri. 22/05 | Sat. 23/05 | Sun. 24/05 | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | |
| Weather | ||||||||||||||||||||||||||||
| Wind (km/h) at 4000m | 30 | 40 | 40 | 45 | 40 | 30 | 40 | 50 | 50 | 60 | 50 | 60 | 60 | 45 | 40 | 40 | 30 | 30 | 30 | 25 | 30 | 20 | 20 | 20 | 20 | 25 | 15 | 10 |
| Wind (km/h) at 2000m | 15 | 15 | 20 | 20 | 15 | 20 | 15 | 10 | 20 | 10 | 15 | 5 | 5 | 5 | 5 | 5 | 5 | 10 | 15 | 10 | 5 | 10 | 15 | 10 | 10 | 15 | 10 | 5 |
Iso 0°CRain-snow limit | ||||||||||||||||||||||||||||
Altitude (m) 4000 3200 2400 1600 800 0 | ||||||||||||||||||||||||||||
| Mon. 18/05 | Tue. 19/05 | Wed. 20/05 | Thu. 21/05 | Fri. 22/05 | Sat. 23/05 | Sun. 24/05 | ||||||||||||||||||||||
Fresh snow (6h) | 0 cm | |||||||||||||||||||||||||||
| Avalanche Risk | ||||||||||||||||||||||||||||
Snow cover North and South at 1500m··· 2000m- - - 2500m | ||||||||||||||||||||||||||||
Total snow depth (cm) 240 160 80 0 | ||||||||||||||||||||||||||||
| Mon. 18/05 | Tue. 19/05 | Wed. 20/05 | Thu. 21/05 | Fri. 22/05 | Sat. 23/05 | Sun. 24/05 | ||||||||||||||||||||||
Snow limit - North face Snow limit - South face | ||||||||||||||||||||||||||||
Snow limit (m) 2700 2400 2100 1800 1500 1200 900 600 300 0 | ||||||||||||||||||||||||||||
| Mon. 18/05 | Tue. 19/05 | Wed. 20/05 | Thu. 21/05 | Fri. 22/05 | Sat. 23/05 | Sun. 24/05 | ||||||||||||||||||||||
| Iso 0°C | RSL | Weather at 1800m |
Wind at 2000m |
Wind at 4000m |
||
|---|---|---|---|---|---|---|
| Mon. 18/05 | 03h | 2 200 | - | 15 | 30 | |
| 09h | 2 100 | 1 700 | 15 | 40 | ||
| 15h | 2 200 | 1 800 | 20 | 40 | ||
| 21h | 2 200 | - | 20 | 45 | ||
| Tue. 19/05 | 03h | 2 200 | - | 15 | 40 | |
| 09h | 2 600 | - | 20 | 30 | ||
| 15h | 2 700 | - | 15 | 40 | ||
| 21h | 2 700 | - | 10 | 50 | ||
| Wed. 20/05 | 03h | 2 700 | 2 400 | 20 | 50 | |
| 09h | 2 600 | - | 10 | 60 | ||
| 15h | 3 000 | - | 15 | 50 | ||
| 21h | 3 200 | - | 5 | 60 | ||
| Thu. 21/05 | 03h | 3 300 | - | 5 | 60 | |
| 09h | 3 800 | - | 5 | 45 | ||
| 15h | 3 900 | - | 5 | 40 | ||
| 21h | 4 000 | - | 5 | 40 | ||
| Fri. 22/05 | 03h | 4 000 | - | 5 | 30 | |
| 09h | 4 000 | - | 10 | 30 | ||
| 15h | 4 000 | - | 15 | 30 | ||
| 21h | 4 100 | - | 10 | 25 | ||
| Sat. 23/05 | 03h | 4 000 | - | 5 | 30 | |
| 09h | 4 000 | - | 10 | 20 | ||
| 15h | 4 000 | - | 15 | 20 | ||
| 21h | 4 100 | - | 10 | 20 | ||
| Sun. 24/05 | 03h | 4 100 | - | 10 | 20 | |
| 09h | 4 000 | - | 15 | 25 | ||
| 15h | 4 000 | - | 10 | 15 | ||
| 21h | 4 100 | - | 5 | 10 | ||
| Avalanche risk |
Snow limit | Snow depth at 2000m |
Fresh snow at 1800m |
|||
| Mon. 18/05 | N : 1 800 m S : 2 000 m | N : 50 cm S : 20 cm | 0 cm | |||
| Tue. 19/05 | N : 1 800 m S : 2 000 m | N : 50 cm S : 15 cm | 0 cm | |||
| Wed. 20/05 | N : 1 900 m S : 2 000 m | N : 45 cm S : 5 cm | 0 cm | |||
| Thu. 21/05 | N : 1 900 m S : 2 100 m | N : 40 cm S : 0 cm | 0 cm | |||
| Fri. 22/05 | N : 1 900 m S : 2 100 m | N : 30 cm S : 0 cm | 0 cm | |||
| Sat. 23/05 | N : 1 900 m S : 2 100 m | N : 25 cm S : 0 cm | 0 cm | |||
| Sun. 24/05 | N : 1 900 m S : 2 100 m | N : 25 cm S : 0 cm | ||||
| French Term | English Term | Definition | Source |
|---|---|---|---|
| Départ spontané | Naturally triggered avalanche | Avalanche not caused by external forces, e.g. snowfall or loss in firmness due to weather conditions. | European Avalanche Warning Services |
| déclenchable | Skier-triggered release | An avalanche caused by the weight of a person (skier, snowboarder, hiker) or by explosives. The additional load collapses a weak layer, causing the slab above to fracture and slide. | AvalancheClarity Static Glossary |
| Ubac | North-facing slopes | The shady, north-facing side of a mountain. Snow persists longer and weak layers are better preserved on ubac slopes. | AvalancheClarity Static Glossary |
| Adret | South-facing slopes | The sunny, south-facing side of a mountain. Snow becomes wet more quickly due to solar radiation. | AvalancheClarity Static Glossary |
| Enneigement | Snow conditions | The depth and distribution of snow on the ground across a mountain range. Varies with elevation, aspect, and snowfall history. | AvalancheClarity Static Glossary |
| ensoleillement | solar radiation | Light and heat energy from the sun. Much of this is in the Ultraviolet part of the electromagnetic spectrum. | Avalanche Center (US) |
| marqué | considerable | Snowpack is moderately to poorly bonded on many steep slopes. Triggering is possible even from low additional loads, particularly on indicated steep slopes. In certain situations, some large natural avalanches are possible. | European Avalanche Warning Services |
| Regel | Refreezing | Overnight freezing of the snow surface forming a hard crust. Refreezing temporarily stabilises the snowpack but strength decreases with daytime warming. | AvalancheClarity Static Glossary |
| Manteau neigeux | Snow cover | Snow deposited on the ground in a multiplicity of layers. | European Avalanche Warning Services |
| Hauteur de neige | Snow depth | Thickness of the snowpack measured vertically. | European Avalanche Warning Services |
| Stabilité | Stability | The strength of a snowpack to withstand internal and external disturbances.Stability is determined by firmness vs. stress inside a snow layer. | European Avalanche Warning Services |
| très fort | very high | Snowpack is generally unstable. Many large natural avalanches are expected, even on moderately steep terrain. Extremely dangerous conditions — avoid all avalanche terrain. | European Avalanche Warning Services |
| Neige humide | Wet snow | The wet snow problem is related to the weakening of the snowpack due to the presence of liquid water. Water infiltrates the snowpack due to high radiation impact (sunshine) which leads to melt or rain (advecting energy into the snowpack leading to melt as well). | European Avalanche Warning Services |
| limité | moderate | Snowpack is moderately well bonded on some steep slopes, otherwise generally well bonded. Triggering is possible with high additional loads, particularly on indicated steep slopes. Large natural avalanches unlikely. | European Avalanche Warning Services |
| moyen | medium | IACS/UNESCO | |
| Arête | Ridges | Narrow crest line of a mountain. | European Avalanche Warning Services |
| Coulée | Sluffs | A small downhill movement of snow. | American Meteorological Society |
| Croûte | Crust | Layer of hard-compacted snow resulting from a melt-freeze process or wind. | European Avalanche Warning Services |
| Névé | Firn | Snow accumulated in recent years, mostly atop glaciers, intensely metamorphosed and denser because of melting and refreezing, as well as from pressures of overlying snow masses. | European Avalanche Warning Services |
| Risque | Risk | Likelihood of occurrence combines mathematical probability, risk exposure and possible damages. | European Avalanche Warning Services |
| dur | hard | IACS/UNESCO | |
| faible | low | Snowpack is generally well bonded and stable. Triggering is generally possible only from high additional loads in a few isolated steep extreme terrain features. Only small natural avalanches possible. | European Avalanche Warning Services |
Bulletin d'estimation du risque d'avalanche
(valable en dehors des pistes balisées et ouvertes)
MASSIF : Mont-Blanc
rédigé le dimanche 24 mai 2026 à 16 h.
Estimation des risques pour le lundi 25 mai 2026
L'humidification du manteau neigeux se poursuit.
Indices de risque : 5 très fort - 4 fort - 3 marqué - 2 limité - 1 faible -- En noir : les pentes les plus dangereuses
Au-dessus de 2800m indice de risque limité, plus bas indice faible.
Départs spontanés : Petits départs au soleil.
Déclenchements skieurs : De la neige humide coule sous les skis au fil du réchauffement.
Stabilité du manteau neigeux jusqu'au lundi 25 mai au soir
Situation avalancheuse typique :Neige humide
Déclenchements provoqués : * Au-dessus de 2800 m : de la neige humide coule sous les skis, de plus en plus facilement au fil du réchauffement par le soleil. Départs plus nombreux en large secteur nord, où l'humidification est encore faible mais gagne progressivement en profondeur. Taille 1 (petite) voir 2 (moyenne) Départs spontanés : * Au-dessus de 2800 m : dans les pentes d'un large secteur nord réchauffées par le soleil : rares départs ponctuels au fil de l'ensoleillement. Taille 1 (petite).
Qualité de la neige
Enneigement :
Pour la saison, l’enneigement est déficitaire sous 2800 m et bon au-dessus. Neige présente en quantité qu'au-dessus de 2000/2200 m en Nord et 2300/2400 m en Sud.
Qualité de la neige ce lundi :
* En dessous de 2300 m : des névés subsistent. Le regel est limité le matin.
* Entre 2300 et 3200m : manteau neigeux printanier : regelé le matin puis humide l'après-midi reposant sur un fond dure. Enfoncement piéton important.
* Au-dessus de 3500 m : Encore un peu de neige froide, poudreuse et dense dans les faces nord (dans les ubacs les plus raides, la limite est plus basse, autour de 3200m). Neige travaillée par le vent vers les crêtes et sommets. En adrets, fine croute non portante le matin qui se ramollit rapidement au soleil.
Aperçu météo pour le lundi 25 mai
| nuit | matin | après-midi | soir | |
|---|---|---|---|---|
| Grand soleil toute la journée avec une grande chaleur presque estivale. Quelques cumulus sur le relief l'après-midi. | ||||
| Pluie-Neige | - | - | - | - |
| Iso 0°C | 4000 m | 4000 m | 4100 m | 4200 m |
| Vent 2000 m | 5 km/h | 5 km/h | 5 km/h | 5 km/h |
| Vent 4000 m | 10 km/h | 10 km/h | 10 km/h | 5 km/h |
Epaisseur de neige hors-piste
Précipitations à 1800 m
Tendance du mardi 26 mai
Indice de risque limité
Risque stationnaire. L'humification en profondeur du manteau progresse nettement en altitude au vu des températures. La stabilisation du manteau neigeux se poursuit.
Conditions nivo-météo des 7 derniers jours
Les 7 derniers jours
| lun. 18/05 | mar. 19/05 | mer. 20/05 | jeu. 21/05 | ven. 22/05 | sam. 23/05 | dim. 24/05 | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | 03h | 09h | 15h | 21h | |
| Météo | ||||||||||||||||||||||||||||
| Vent (km/h) à 4000m | 30 | 40 | 40 | 45 | 40 | 30 | 40 | 50 | 50 | 60 | 50 | 60 | 60 | 45 | 40 | 40 | 30 | 30 | 30 | 25 | 30 | 20 | 20 | 20 | 20 | 25 | 15 | 10 |
| Vent (km/h) à 2000m | 15 | 15 | 20 | 20 | 15 | 20 | 15 | 10 | 20 | 10 | 15 | 5 | 5 | 5 | 5 | 5 | 5 | 10 | 15 | 10 | 5 | 10 | 15 | 10 | 10 | 15 | 10 | 5 |
Iso 0°CLimite pluie-neige | ||||||||||||||||||||||||||||
Altitude en m 4000 3200 2400 1600 800 0 | ||||||||||||||||||||||||||||
| lun. 18/05 | mar. 19/05 | mer. 20/05 | jeu. 21/05 | ven. 22/05 | sam. 23/05 | dim. 24/05 | ||||||||||||||||||||||
Neige fraîche (6h) | 0 cm | |||||||||||||||||||||||||||
| Risque d'Avalanche | ||||||||||||||||||||||||||||
Enneigement versant Nord et Sud à 1500m··· 2000m- - - 2500m | ||||||||||||||||||||||||||||
Hauteur totale de neige (cm) 240 160 80 0 | ||||||||||||||||||||||||||||
| lun. 18/05 | mar. 19/05 | mer. 20/05 | jeu. 21/05 | ven. 22/05 | sam. 23/05 | dim. 24/05 | ||||||||||||||||||||||
Limite de l'enneigement - Versant Nord Limite de l'enneigement - Versant Sud | ||||||||||||||||||||||||||||
Limite d'enneigement (m) 2700 2400 2100 1800 1500 1200 900 600 300 0 | ||||||||||||||||||||||||||||
| lun. 18/05 | mar. 19/05 | mer. 20/05 | jeu. 21/05 | ven. 22/05 | sam. 23/05 | dim. 24/05 | ||||||||||||||||||||||
| Iso 0°C | LPN | Météo à 1800m |
Vent à 2000m |
Vent à 4000m |
||
|---|---|---|---|---|---|---|
| lun. 18/05 | 03h | 2 200 | - | 15 | 30 | |
| 09h | 2 100 | 1 700 | 15 | 40 | ||
| 15h | 2 200 | 1 800 | 20 | 40 | ||
| 21h | 2 200 | - | 20 | 45 | ||
| mar. 19/05 | 03h | 2 200 | - | 15 | 40 | |
| 09h | 2 600 | - | 20 | 30 | ||
| 15h | 2 700 | - | 15 | 40 | ||
| 21h | 2 700 | - | 10 | 50 | ||
| mer. 20/05 | 03h | 2 700 | 2 400 | 20 | 50 | |
| 09h | 2 600 | - | 10 | 60 | ||
| 15h | 3 000 | - | 15 | 50 | ||
| 21h | 3 200 | - | 5 | 60 | ||
| jeu. 21/05 | 03h | 3 300 | - | 5 | 60 | |
| 09h | 3 800 | - | 5 | 45 | ||
| 15h | 3 900 | - | 5 | 40 | ||
| 21h | 4 000 | - | 5 | 40 | ||
| ven. 22/05 | 03h | 4 000 | - | 5 | 30 | |
| 09h | 4 000 | - | 10 | 30 | ||
| 15h | 4 000 | - | 15 | 30 | ||
| 21h | 4 100 | - | 10 | 25 | ||
| sam. 23/05 | 03h | 4 000 | - | 5 | 30 | |
| 09h | 4 000 | - | 10 | 20 | ||
| 15h | 4 000 | - | 15 | 20 | ||
| 21h | 4 100 | - | 10 | 20 | ||
| dim. 24/05 | 03h | 4 100 | - | 10 | 20 | |
| 09h | 4 000 | - | 15 | 25 | ||
| 15h | 4 000 | - | 10 | 15 | ||
| 21h | 4 100 | - | 5 | 10 | ||
| Risque avalanche |
Limite enneigement | Enneigement à 2000m |
Neige fraîche à 1800m |
|||
| lun. 18/05 | N : 1 800 m S : 2 000 m | N : 50 cm S : 20 cm | 0 cm | |||
| mar. 19/05 | N : 1 800 m S : 2 000 m | N : 50 cm S : 15 cm | 0 cm | |||
| mer. 20/05 | N : 1 900 m S : 2 000 m | N : 45 cm S : 5 cm | 0 cm | |||
| jeu. 21/05 | N : 1 900 m S : 2 100 m | N : 40 cm S : 0 cm | 0 cm | |||
| ven. 22/05 | N : 1 900 m S : 2 100 m | N : 30 cm S : 0 cm | 0 cm | |||
| sam. 23/05 | N : 1 900 m S : 2 100 m | N : 25 cm S : 0 cm | 0 cm | |||
| dim. 24/05 | N : 1 900 m S : 2 100 m | N : 25 cm S : 0 cm | ||||