The lake sparkles and clouds lift from Mont Blanc from spring to fall; November tends to be drizzly gray, and then winter brightens things up above the plain (as they call the flatter terrain surrounding the lake). Crowds monopolize Montreux and Chillon year-round but overwhelm it in July (jazz festival time) and August (Europe-wide vacations). It's worth aiming for concert and dance season in Lausanne: from September through May. Prime ski time in the Alpes Vaudoises is from late December through Easter, and prices go up accordingly. Remember that at these latitudes summer daylight extends until 9 pm", allowing you to pack a lot into one day; the reverse is true in winter.