A cold front saw temperatures fall last week and over the weekend, with many places in the lowlands experiencing ground frost.
With the snow level dropping to 1,500m and heavy precipitation in many parts, on Monday many alpine resorts woke up to fresh snow on the ground.
“Winter is coming, how to resist?” tweeted Verbier, its webcam pictures looking distinctly wintry.
Laax, St Moritz, the Jungfrau region and Crans-Montana were among the other resorts whose webcams showed snow on Monday.
So does this mean the definitive end of summer? Unfortunately MeteoSuisse thinks so.
Writing on Sunday, the federal meteorologists compared the month of September this year with 2016, and found it was unlikely we would see a return to warm weather.
As in 2016, average temperatures dropped below 16 degrees in the middle of the month. But whereas in 2016 that was preceded by 11 hot days above 25 degrees, this year temperatures in the first half of the month were lower, with only seven days exceeding 20 degrees.
Though temperatures may go up slightly, we are unlikely to see a “spectacular rise” in temperatures in the second half of the month as the cold air has settled over the country for several days already, said MeteoSuisse.
Prediction models show the maximum temperature is likely to remain below 20 degrees for the rest of the month.
Based on Geneva's weather, temperatures for this September are likely to be between 0.7 and 1.9 degrees below the norm for this time of year.
“Everything tells us that summer is well and truly over,” meteorologists concluded.
Roll on the ski season then...