Here are the average weather stats for Zurich (from the BBC). Cities at similar elevations (400-600m) will be pretty similar to that, for higher elevation take off an average of 0.6 degrees C per 100 metres of elevation increase (therefore, a town at 1000 metres will be about 3 degrees colder than Zurich, on average). However, there are many local variations that make it WAY more complicated. In general, reasonably cold at lower elevations (maybe around 0), and bloody cold on top of a mountain (maybe -20 or lower).