Lac d'Émosson

Lake High-altitude reservoir behind a dramatic dam

Reservoir formed by the Émosson Dam on the Valais‑Haute‑Savoie border; accessed by mountain roads and lifts, it draws hikers, photographers and those interested in alpine engineering and views toward Mont Blanc.

Main image

Lac d’Émosson is a high-altitude reservoir in the Swiss canton of Valais near the Franco-Swiss border. It is a purpose-built storage lake supplying water for downstream hydroelectric plants.

The lakeshore and surrounding ridges offer mountain walking and short hikes that are popular in summer, with panoramic views over steep valley walls and the dam structure. Boat access is limited and much of the activity focuses on trails and viewpoints rather than water sports.

The lake exists because of dam and reservoir works constructed to regulate alpine runoff for power generation and water storage; the valley and infrastructure have been adapted for that industrial purpose. Over time service roads and hiking routes have made the area more accessible to non-industrial visitors.

It lies above the Valais valleys, close to the Swiss-French border in the high Alps, within reach of valley towns in the region and surrounded by steep, glaciated slopes.

  • Function: Sits at high alpine elevation and is a man-made storage reservoir used in regional hydroelectric schemes.
Lac d'Émosson
Lac d'Émosson reservoir, near Finhaut, Valais, Switzerland
46.0860, 6.9101
Free (access to dam and facilities may have fees for parking or guided tours)

How to Get to Lac d'Émosson #

From Martigny or Chamonix: drive to Finhaut then take the Émosson train/funiculaire or follow the mountain road to the dam parking. Seasonal lifts and train services run from valley stations; check local timetables.

Tips for Visiting Lac d'Émosson #

  • Take the mountain train or the inclined lift (Le Funiculaire) from the valley for dramatic approaches and great photo angles.
  • Walk the engineered paths on the dam to appreciate the scale and the drop - mornings have the best light for the reservoir's turquoise water.
  • Combine with hikes up to nearby peaks (e.g., Lac Bleu viewpoints) for glacier views and alpine meadows.

Best Time to Visit Lac d'Émosson #

Summer and early autumn are best for hiking and accessing the dam; winter access is limited and roads may close.

Summer
June-September · 5-18°C (41-64°F)
Best for hiking and for seeing the reservoir at its most vivid turquoise.
Autumn
September-October · 0-12°C (32-54°F)
Clear air and crisp light; higher risk of early snow toward October.

Weather & Climate near Lac d'Émosson #

Climate

Lac d'Émosson's climate is classified as Subarctic - Subarctic climate with cool summers (peaking in August) and freezing winters (coldest in January). Temperatures range from -8°C to 16°C. Abundant rainfall (1666 mm/year), wettest in December, distributed fairly evenly throughout the year.

Best Time to Visit
AugustJulySeptember
Temperature & Rainfall
Temperature Range
28°
Warmest Month
-29°
Coldest Month
Monthly Conditions

January

January is the coldest month with highs of -2°C and lows of -8°C. Significant rainfall (157 mm) and mostly overcast skies.

27 Poor

Comfort

-5°
Feels Like Freezing
-5°C
Temperature
-8° -2°
86%
Humidity
Very Humid

Weather

157 mm
Rainfall
4.1 m/s
Wind
Light Breeze
0.1
UV Index
Low
8.9h daylight

February

February is freezing with highs of -2°C and lows of -8°C. Significant rainfall (159 mm) and mostly overcast skies.

27 Poor

Comfort

-5°
Feels Like Freezing
-5°C
Temperature
-8° -2°
87%
Humidity
Very Humid

Weather

159 mm
Rainfall
4.3 m/s
Wind
Light Breeze
0.3
UV Index
Low
10.2h daylight

March

March is freezing with highs of 0°C and lows of -6°C. Significant rainfall (133 mm) and partly cloudy skies.

33 Poor

Comfort

-3°
Feels Like Freezing
-3°C
Temperature
-6°
86%
Humidity
Very Humid

Weather

133 mm
Rainfall
4.3 m/s
Wind
Light Breeze
0.6
UV Index
Moderate
11.8h daylight

April

April is freezing with highs of 2°C and lows of -4°C. Significant rainfall (133 mm) and partly cloudy skies.

42 Poor

Comfort

-1°
Feels Like Freezing
-1°C
Temperature
-4°
80%
Humidity
Very Humid

Weather

133 mm
Rainfall
4.0 m/s
Wind
Light Breeze
1.0
UV Index
High
13.4h daylight

May

May is cold with highs of 7°C and lows of 0°C. Significant rainfall (140 mm) and mostly overcast skies.

40 Poor

Comfort

Feels Like Cold
C
Temperature
79%
Humidity
Very Humid

Weather

140 mm
Rainfall
3.8 m/s
Wind
Light Breeze
1.4
UV Index
High
14.8h daylight

June

June is cold with highs of 11°C and lows of 4°C. Significant rainfall (129 mm) and partly cloudy skies.

52 Acceptable

Comfort

Feels Like Cold
C
Temperature
11°
77%
Humidity
Very Humid

Weather

129 mm
Rainfall
3.7 m/s
Wind
Light Breeze
1.7
UV Index
Very High
15.6h daylight

July

July is cool with highs of 15°C and lows of 6°C. Significant rainfall (109 mm) and partly cloudy skies.

56 Acceptable

Comfort

11°
Feels Like Cool
11°C
Temperature
15°
75%
Humidity
Very Humid

Weather

109 mm
Rainfall
3.6 m/s
Wind
Light Breeze
1.8
UV Index
Very High
15.2h daylight

August

August is cool with highs of 16°C and lows of 7°C. Significant rainfall (115 mm) and partly cloudy skies.

64 Good

Comfort

11°
Feels Like Cool
11°C
Temperature
16°
74%
Humidity
Very Humid

Weather

115 mm
Rainfall
3.5 m/s
Wind
Light Breeze
1.5
UV Index
High
14.0h daylight

September

September is cold with highs of 12°C and lows of 4°C. Significant rainfall (107 mm) and partly cloudy skies.

54 Acceptable

Comfort

Feels Like Cold
C
Temperature
12°
77%
Humidity
Very Humid

Weather

107 mm
Rainfall
3.6 m/s
Wind
Light Breeze
1.0
UV Index
Moderate
12.4h daylight

October

October is cold with highs of 8°C and lows of 1°C. Significant rainfall (143 mm) and partly cloudy skies.

44 Poor

Comfort

Feels Like Cold
C
Temperature
78%
Humidity
Very Humid

Weather

143 mm
Rainfall
3.8 m/s
Wind
Light Breeze
0.5
UV Index
Moderate
10.7h daylight

November

November is freezing with highs of 2°C and lows of -4°C. Significant rainfall (168 mm) and mostly overcast skies.

28 Poor

Comfort

-1°
Feels Like Freezing
-1°C
Temperature
-4°
84%
Humidity
Very Humid

Weather

168 mm
Rainfall
4.3 m/s
Wind
Light Breeze
0.2
UV Index
Low
9.3h daylight

December

December is freezing with highs of -1°C and lows of -6°C. The wettest month with heavy rain (173 mm) and mostly overcast skies.

27 Poor

Comfort

-4°
Feels Like Freezing
-4°C
Temperature
-6° -1°
84%
Humidity
Very Humid

Weather

173 mm
Rainfall
4.3 m/s
Wind
Light Breeze
0.1
UV Index
Low
8.5h daylight

Nearby Attractions to Lac d'Émosson