Mont-Blanc
Moderate 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
Bulletin date: Monday, May 18, 2026 at 04:00 PM
Valid until:
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 Monday 18 May 2026 at 4:00 PM.
Risk assessment for Tuesday 19 May 2026
Wintry snow cover at altitude with 50/60 cm of new snow above 3000 m.
Risk indices: 5 very high - 4 high - 3 considerable - 2 moderate - 1 low -- In black: the most dangerous slopes
Above 2500m moderate risk index, lower down low index.
Naturally triggered avalanches: Wet snow as it moistens.
Skier-triggered releases: A few wind slabs in the cold new snow at altitude.
Stability of the snow cover until Tuesday 19 May evening
Typical avalanche situation :
Wind slab
Wet snow
Skier-triggered releases: * In the high mountains (mainly on the Mont-Blanc side), there are a few wind slabs. Already formed by the West wind in the new snow at the time of the snowfall. Above 3000 m near crests and ridges, they are more numerous and reactive. Size 1 (small) to 2 (medium). Observable signs: cracks under skis, new snow accumulation, surface ripples ... * New snow can sluff under skis mainly below 3000 m. Becoming increasingly easy as it moistens due to temperatures rising significantly in the afternoon. Size 1 (small) to 2 (medium). Naturally triggered avalanches: * A few point-release avalanches of new snow at all altitudes and aspects. These releases mainly occur in the afternoon given that temperatures are rising quite significantly. Size 1, rarely 2.
Snow quality
Snow conditions:
For the season, snow cover is below average below 2700 m and good above. There are traces of new snow on the ground from 1700 m, and underlying layers are only truly present above 2000m on North aspects and 2300m on South aspects.
Snow quality this Monday:
* Below 2000/2300 m: 5/15 cm of new snow without an underlying layer (it locally rests on some firn). The new snow is already settled and moist on the surface.
* Between 2000/2300 m and 3000 m: 20/40 cm of new snow on a hard base. It is densified and heavier on the surface. Weak refreezing in the morning.
* Above 3000 m: 40/60 cm of new snow (very irregular depths, in snow dunes there may be even greater accumulations), cold and light on most slopes. Towards the ridges and on exposed slopes, it is wind-affected. Significant foot penetration.
Weather overview for Tuesday 19 May
| night | morning | afternoon | evening | |
|---|---|---|---|---|
 |  |  |  | |
| Ciel clair au lever du soleil. En matinée, les nuages arrivent rapidement et des pluies sont attendues. Ensuite, le ciel reste couvert. | ||||
| Rain-Snow | 1800m | 1900m | - | - |
| Iso 0°C | 2200 m | 2800 m | 2800 m | 2800 m |
| Wind 2000 m | 15 km/h | 20 km/h | 25 km/h | 15 km/h |
| Wind 4000 m | 45 km/h | 45 km/h | 50 km/h | 40 km/h |
Off-piste snow depth
Precipitation at 1800 m
Trend for Wednesday 20 May
Risk index moderate
Return to blue skies and seasonal temperatures. The snow cover is undergoing moistening at all altitudes.
Snow-weather conditions for the last 7 days
Last 7 days
| Tue. 12/05 | Wed. 13/05 | Thu. 14/05 | Fri. 15/05 | Sat. 16/05 | Sun. 17/05 | Mon. 18/05 | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 | 100 | 110 | 60 | 50 | 45 | 55 | 70 | 70 | 65 | 70 | 60 | 60 | 40 | 40 | 30 | 35 | 40 | 45 | 35 | 40 | 40 | 25 | 25 | 35 | 30 | 40 | 40 | 45 |
| Wind (km/h) at 2000m | 40 | 15 | 10 | 10 | 10 | 15 | 25 | 40 | 30 | 40 | 50 | 30 | 20 | 20 | 20 | 30 | 20 | 10 | 10 | 10 | 10 | 5 | 10 | 15 | 15 | 15 | 20 | 20 |
Iso 0°CRain-snow limit | ||||||||||||||||||||||||||||
Altitude (m) 2400 1600 800 0 | ||||||||||||||||||||||||||||
| Tue. 12/05 | Wed. 13/05 | Thu. 14/05 | Fri. 15/05 | Sat. 16/05 | Sun. 17/05 | Mon. 18/05 | ||||||||||||||||||||||
Fresh snow (6h) | ||||||||||||||||||||||||||||
| Avalanche Risk | ||||||||||||||||||||||||||||
Snow cover North and South at 1500m··· 2000m- - - 2500m | ||||||||||||||||||||||||||||
Total snow depth (cm) 240 160 80 0 | ||||||||||||||||||||||||||||
| Tue. 12/05 | Wed. 13/05 | Thu. 14/05 | Fri. 15/05 | Sat. 16/05 | Sun. 17/05 | Mon. 18/05 | ||||||||||||||||||||||
Snow limit - North face Snow limit - South face | ||||||||||||||||||||||||||||
Snow limit (m) 2400 2100 1800 1500 1200 900 600 300 0 | ||||||||||||||||||||||||||||
| Tue. 12/05 | Wed. 13/05 | Thu. 14/05 | Fri. 15/05 | Sat. 16/05 | Sun. 17/05 | Mon. 18/05 | ||||||||||||||||||||||
| Iso 0°C | RSL | Weather at 1800m |
Wind at 2000m |
Wind at 4000m |
||
|---|---|---|---|---|---|---|
| Tue. 12/05 | 03h | 1 700 | 1 400 | | 40 | 100 |
| 09h | 1 600 | - | | 15 | 110 | |
| 15h | 2 100 | - | | 10 | 60 | |
| 21h | 2 100 | - | | 10 | 50 | |
| Wed. 13/05 | 03h | 2 200 | - | | 10 | 45 |
| 09h | 2 200 | - | | 15 | 55 | |
| 15h | 2 200 | - | | 25 | 70 | |
| 21h | 2 100 | - | | 40 | 70 | |
| Thu. 14/05 | 03h | 1 600 | 1 200 | | 30 | 65 |
| 09h | 1 700 | 1 300 | | 40 | 70 | |
| 15h | 1 800 | 1 400 | | 50 | 60 | |
| 21h | 1 600 | 1 300 | | 30 | 60 | |
| Fri. 15/05 | 03h | 1 500 | 1 100 | | 20 | 40 |
| 09h | 1 400 | 1 000 | | 20 | 40 | |
| 15h | 1 500 | 1 200 | | 20 | 30 | |
| 21h | 1 300 | 1 000 | | 30 | 35 | |
| Sat. 16/05 | 03h | 1 400 | 1 000 | | 20 | 40 |
| 09h | 1 500 | - | | 10 | 45 | |
| 15h | 1 800 | 1 400 | | 10 | 35 | |
| 21h | 1 800 | - | | 10 | 40 | |
| Sun. 17/05 | 03h | 1 800 | - | | 10 | 40 |
| 09h | 2 000 | - | | 5 | 25 | |
| 15h | 2 300 | - | | 10 | 25 | |
| 21h | 2 300 | - | | 15 | 35 | |
| 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 | |
| Avalanche risk |
Snow limit | Snow depth at 2000m |
Fresh snow at 1800m |
|||
| Tue. 12/05 | N : 1 700 m S : 1 700 m | N : 50 cm S : 5 cm | 0 cm | |||
| Wed. 13/05 | N : 1 700 m S : 1 700 m | N : 50 cm S : 5 cm | 10 cm | |||
| Thu. 14/05 | N : 1 300 m S : 1 300 m | N : 60 cm S : 15 cm | 15 cm | |||
| Fri. 15/05 | N : 1 300 m S : 1 300 m | N : 65 cm S : 20 cm | 12 cm | |||
| Sat. 16/05 | N : 1 400 m S : 1 500 m | N : 75 cm S : 30 cm | 5 cm | |||
| Sun. 17/05 | N : 1 500 m S : 1 600 m | N : 65 cm S : 25 cm | 0 cm | |||
| Mon. 18/05 | N : 1 800 m S : 2 000 m | N : 50 cm S : 20 cm | ||||
| French Term | English Term | Definition | Source |
|---|---|---|---|
| Départ spontané | Naturally triggered avalanches | Avalanche not caused by external forces, e.g. snowfall or loss in firmness due to weather conditions. | European Avalanche Warning Services |
| déclenchable | Skier-triggered releases | 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 |
| Accumulation | Snow accumulation | Wind-deposited snow, often in significant depth behind ridges and obstacles. Accumulations form dangerous wind slabs. | AvalancheClarity Static Glossary |
| Sous-couche | Underlying layers | A buried snow layer beneath more recent layers. A weak underlying layer can fail under load and trigger slab avalanches. | 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 |
| 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 |
| Accumulations | Snow dunes | Snow deposits formed by wind-transported snow. Ripples are small transversal depositional features. Dunes are typically larger in scale and often Barchanoid. | European Avalanche Warning Services |
| Neige ventée | Wind slabs | The wind-drifted snow problem is related to wind-drifted snow. The transported snow is typically packed on leeward sides into gullies, bowls and behind ridgelines or other wind-sheltered locations. Also commonly known as “windslab”. The problem is less widespread distributed than the new snow problem. | 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 fraîche | New snow | The new snow problem is related to current or recent snowfall. The additional loading on the existing snowpack or a lack of cohesion in the newly fallen snow can cause avalanche activity. The problem is widely present, often in all aspects and lasts usually until a few days after the snowfall event. | 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 |
| Exposé | Exposed | Exposure to wind, sun, avalanches or other general danger. | European Avalanche Warning Services |
| Exposition | Aspects | Direction in which a slope faces as indicated by compass direction of the fall line; i.e. a north slope faces in a northerly direction. | European Avalanche Warning Services |
| moyen | medium | IACS/UNESCO | |
| Arête | Ridges | Narrow crest line of a mountain. | European Avalanche Warning Services |
| légèrement humide | moist | IACS/UNESCO | |
| Coulée | Sluff | A small downhill movement of snow. | American Meteorological Society |
| 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 lundi 18 mai 2026 à 16 h.
Estimation des risques pour le mardi 19 mai 2026
Manteau neigeux hivernal en altitude avec 50/60 cm de neige récente au-dessus de 3000 m.
Indices de risque : 5 très fort - 4 fort - 3 marqué - 2 limité - 1 faible -- En noir : les pentes les plus dangereuses
Au-dessus de 2500m indice de risque limité, plus bas indice faible.
Départs spontanés : Neige humide au fil de l'humidification.
Déclenchements skieurs : Quelques plaques à vent dans la neige récente froide en altitude.
Stabilité du manteau neigeux jusqu'au mardi 19 mai au soir
Situation avalancheuse typique :Neige ventéeNeige humide
Déclenchements provoqués : * En haute-montagne (principalement du côté Mont-Blanc), on retrouve quelques plaques à vent. Déjà formées par le vent d'Ouest dans la neige récente au moment des chutes de neige. Au-dessus de 3000 m à proximité des crêtes et arêtes, elles sont plus nombreuses et réactives. Taille 1 (petite) à 2 (moyenne). Observables : fissures sous les skis, accumulation de neige récente, vaguelettes en surface ... * De la neige récente peut couler sous les skis principalement sous 3000 m. De plus en plus facile au fil de l'humidification dû aux températures qui remontent nettement l'après-midi. Taille 1 (petite) à 2 (moyenne). Départs spontanés : * Quelques départs ponctuels de neige récente à toutes altitudes et orientations. Ces départs concernent principalement l'après-midi au vu des températures qui remontent assez nettement. Taille 1, rarement 2.
Qualité de la neige
Enneigement :
Pour la saison, l’enneigement est déficitaire sous 2700 m et bon au-dessus. On retrouve des traces de neige récente au sol à partir de 1700 m, et les sous-couches ne sont réellement présentes qu'au-dessus de 2000m en Nord et 2300m en Sud.
Qualité de la neige ce lundi :
* En dessous de 2000/2300 m : 5/15 cm de neige récente sans sous-couche (elle repose localement sur quelques névés). La neige récente est déjà tassée et légèrement humide en surface.
* Entre 2000/2300 m et 3000 m : 20/40 cm de neige récente sur un fond dur. Elle est densifiée et alourdie en surface. Faible regel le matin.
* Au-dessus de 3000 m : 40/60 cm de neige récente (épaisseurs très irrégulières, dans les accumulations on peut avoir des cumuls encore plus importants) froide et légère dans la plupart des pentes. Vers les crêtes/arêtes et dans les pentes exposées, elle est travaillée par le vent. Enfoncement piéton important.
Aperçu météo pour le mardi 19 mai
| nuit | matin | après-midi | soir | |
|---|---|---|---|---|
| | | | |
| Ciel clair au lever du soleil. En matinée, les nuages arrivent rapidement et des pluies sont attendues. Ensuite, le ciel reste couvert. | ||||
| Pluie-Neige | 1800m | 1900m | - | - |
| Iso 0°C | 2200 m | 2800 m | 2800 m | 2800 m |
| Vent 2000 m | 15 km/h | 20 km/h | 25 km/h | 15 km/h |
| Vent 4000 m | 45 km/h | 45 km/h | 50 km/h | 40 km/h |
Epaisseur de neige hors-piste
Précipitations à 1800 m
Tendance du mercredi 20 mai
Indice de risque limité
Retour au ciel bleu et aux températures de saisons. Le manteau neigeux subit une humidification à toutes altitudes.
Conditions nivo-météo des 7 derniers jours
Les 7 derniers jours
| mar. 12/05 | mer. 13/05 | jeu. 14/05 | ven. 15/05 | sam. 16/05 | dim. 17/05 | lun. 18/05 | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 | 100 | 110 | 60 | 50 | 45 | 55 | 70 | 70 | 65 | 70 | 60 | 60 | 40 | 40 | 30 | 35 | 40 | 45 | 35 | 40 | 40 | 25 | 25 | 35 | 30 | 40 | 40 | 45 |
| Vent (km/h) à 2000m | 40 | 15 | 10 | 10 | 10 | 15 | 25 | 40 | 30 | 40 | 50 | 30 | 20 | 20 | 20 | 30 | 20 | 10 | 10 | 10 | 10 | 5 | 10 | 15 | 15 | 15 | 20 | 20 |
Iso 0°CLimite pluie-neige | ||||||||||||||||||||||||||||
Altitude en m 2400 1600 800 0 | ||||||||||||||||||||||||||||
| mar. 12/05 | mer. 13/05 | jeu. 14/05 | ven. 15/05 | sam. 16/05 | dim. 17/05 | lun. 18/05 | ||||||||||||||||||||||
Neige fraîche (6h) | ||||||||||||||||||||||||||||
| Risque d'Avalanche | ||||||||||||||||||||||||||||
Enneigement versant Nord et Sud à 1500m··· 2000m- - - 2500m | ||||||||||||||||||||||||||||
Hauteur totale de neige (cm) 240 160 80 0 | ||||||||||||||||||||||||||||
| mar. 12/05 | mer. 13/05 | jeu. 14/05 | ven. 15/05 | sam. 16/05 | dim. 17/05 | lun. 18/05 | ||||||||||||||||||||||
Limite de l'enneigement - Versant Nord Limite de l'enneigement - Versant Sud | ||||||||||||||||||||||||||||
Limite d'enneigement (m) 2400 2100 1800 1500 1200 900 600 300 0 | ||||||||||||||||||||||||||||
| mar. 12/05 | mer. 13/05 | jeu. 14/05 | ven. 15/05 | sam. 16/05 | dim. 17/05 | lun. 18/05 | ||||||||||||||||||||||
| Iso 0°C | LPN | Météo à 1800m |
Vent à 2000m |
Vent à 4000m |
||
|---|---|---|---|---|---|---|
| mar. 12/05 | 03h | 1 700 | 1 400 | | 40 | 100 |
| 09h | 1 600 | - | | 15 | 110 | |
| 15h | 2 100 | - | | 10 | 60 | |
| 21h | 2 100 | - | | 10 | 50 | |
| mer. 13/05 | 03h | 2 200 | - | | 10 | 45 |
| 09h | 2 200 | - | | 15 | 55 | |
| 15h | 2 200 | - | | 25 | 70 | |
| 21h | 2 100 | - | | 40 | 70 | |
| jeu. 14/05 | 03h | 1 600 | 1 200 | | 30 | 65 |
| 09h | 1 700 | 1 300 | | 40 | 70 | |
| 15h | 1 800 | 1 400 | | 50 | 60 | |
| 21h | 1 600 | 1 300 | | 30 | 60 | |
| ven. 15/05 | 03h | 1 500 | 1 100 | | 20 | 40 |
| 09h | 1 400 | 1 000 | | 20 | 40 | |
| 15h | 1 500 | 1 200 | | 20 | 30 | |
| 21h | 1 300 | 1 000 | | 30 | 35 | |
| sam. 16/05 | 03h | 1 400 | 1 000 | | 20 | 40 |
| 09h | 1 500 | - | | 10 | 45 | |
| 15h | 1 800 | 1 400 | | 10 | 35 | |
| 21h | 1 800 | - | | 10 | 40 | |
| dim. 17/05 | 03h | 1 800 | - | | 10 | 40 |
| 09h | 2 000 | - | | 5 | 25 | |
| 15h | 2 300 | - | | 10 | 25 | |
| 21h | 2 300 | - | | 15 | 35 | |
| 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 | |
| Risque avalanche |
Limite enneigement | Enneigement à 2000m |
Neige fraîche à 1800m |
|||
| mar. 12/05 | N : 1 700 m S : 1 700 m | N : 50 cm S : 5 cm | 0 cm | |||
| mer. 13/05 | N : 1 700 m S : 1 700 m | N : 50 cm S : 5 cm | 10 cm | |||
| jeu. 14/05 | N : 1 300 m S : 1 300 m | N : 60 cm S : 15 cm | 15 cm | |||
| ven. 15/05 | N : 1 300 m S : 1 300 m | N : 65 cm S : 20 cm | 12 cm | |||
| sam. 16/05 | N : 1 400 m S : 1 500 m | N : 75 cm S : 30 cm | 5 cm | |||
| dim. 17/05 | N : 1 500 m S : 1 600 m | N : 65 cm S : 25 cm | 0 cm | |||
| lun. 18/05 | N : 1 800 m S : 2 000 m | N : 50 cm S : 20 cm | ||||