On 8 August 2025, we made the following observations at the Chaltwasser Glacier:
Chaltwasser Glacier largely free of snow on 8 August 2025.
The northern glacier lake can be seen at the foot of the glacier terminus.
Since our visit on
11 July 2022, the Chaltwasser Glacier has continued to lose size and mass. The glacier terminus has flattened and narrowed.
The Chaltwasser Glacier currently ends at an altitude of approximately 2740 metres above sea level.
By comparison, the Rhone Glacier ends at 2200 metres and the Unteraargletscher at just 1950 metres above sea level.
Glacier tongue of the Chaltwasser Glacier on 8 August 2025.
The glacier terminus reached almost to the northern glacier lake.
Crossing the glacier terminus
Since the lake was 100% free of snow and ice, we had to cross the glacier in the area of the tongue. This was easier this year than
11 July 2022.
Northern lake in front of the Chaltwasser Glacier from the southeast on 8 August 2025.
Northern lake and tongue of the Chaltwasser Glacier from the northwest on 8 August 2025.
Since our last visit on
11 July 2022, the northern glacial lake has grown in size towards the north (left in the image). Presumably, ice that was protected from direct sunlight under the debris melted, creating space for the lake to expand.
Area between the northern glacier lake and the glacier terminus on 8 August 2025.
Overview of the southern glacial lake in front of the Chaltwasser Glacier on 8 August 2025.
View approx. from SE.
Eastern arm of the southern glacier lake in front of the Chaltwasser Glacier on 8 August 2025.
Dam between the northern and southern glacial lakes in front of the Chaltwasser Glacier on 8 August 2025.
Drainage of the northern glacier lake into the southern glacier lake on 8 August 2025.
Legend:
1) Northern glacial lake.
2) Drainage of meltwater from the northern to the southern glacier lake.
3) Southern glacial lake.
The level of the northern glacial lake is 2-3 metres higher than that of the southern glacial lake.
The colour of the northern glacier lake is lighter because sediments are washed into the northern lake by the glacier. Some of these sediments sink to the bottom of the northern lake and are deposited there. As a result, the water that flows into the northern glacier lake contains fewer sediments. The colour of the southern lake is therefore darker.
Meltwater below the glacier on 8 August 2025 at 7:50 a.m.
Meltwater below the glacier on 8 August 2025 at 3:20 p.m.
Temperatures:
- 11° on the Simplon Pass at 6 a.m.
- 14° in front of the Chaltwasser Glacier at 11 a.m.
Zero degree limit: 4700m above sea level (forecast by MeteoSchweiz)
Over the previous seven days, the zero degree line lay between 2600m and 4500m above sea level, averaging 3540m above sea level.