With a strong northwestern wind, the last warmth is blown away from the mountains.
A low pressure system with its core located in southern Finland and a high pressure system over Ireland creates ideal circumstances for a first touch of a “Nordstau”. Cold air from the arctic sweeps over the Atlantic and North Sea, picking up a lot of moist from these warm waters.
When flowing south, they hit the main walls of the Alps. This results in strong precipitation, combined with relatively cold weather at altitude. Up to 30cm of fresh snow can fall on the north side of the Alps whilst the south side is enjoying blue skies and high temperatures.
This is quite a welcome change, after a dramatically hot summer in this part (and other parts) of Europe. Glacial melting has beaten all records and an early touch of King Winter is therefore a good thing.
Whether this marks a longer period of cooler weather in the mountains is far from sure. It is however the definitive end of high-altitude hiking for this season. Multiple mountain passes, such as the Furkapas, Grimselpass and Nufenenpass will close per 20h on the 16th of September.