Snow is melting earlier
In Arosa, the maximum snow depth has reduced by 20 percent. It decreased from an average of around 120 cm (1961‒1990) to approximately 100 cm (1991‒2020). Today, the winter snow cover begins to melt on average one month earlier than it did in the comparison period of 1961‒1990. Nowadays, there is an average of 40 cm of snow left around 20th April, whereas in the comparison period of 1961‒1990, Arosa still had an average of around 1 m of snow by the same date.
It is interesting to note that, while there was very little change in the accumulation of snow cover between the two comparison periods of 1981‒2010 and 1991‒2020, the snow melt has been starting noticeably earlier in the last 30 years.
The delayed accumulation of snow cover and the earlier snow melt have a considerable impact on the duration of snow-cover periods.
In earlier times, we could expect the average depth of snow cover to be at least 40 cm from the beginning of December to 10th May. Today, the 40-cm minimum snow depth in Arosa is only seen from the middle of December to 20th April, on average. The period with at least 40 cm of snow cover has therefore shortened from just under five and a half months to just over four months.
Snow cover of at least 80 cm used to be present in Arosa from the middle of January until the end of April, on average. Now, however, this snow depth is only found in Arosa from the end of January to the end of March. This is a reduction from three and a half months down to two.