In the US, many mountainous regions have roads closed until early summer. I'd like to spend a couple weeks in Switz and Austria, as early in the summer (i.e. May) as possible, but will I run up against limitations due to snow? Thanks...
The high passes in Switzerland do not usually open until the beginning to middle June. The "Touring Club Suisse" site (the equivalent of the AAA) has accurate information. I am not sure about Austria.
Late May to early June timeframe is usually when the Alpine summer season begins. There's still snow on the upper peaks, but most of the snow on the lower slopes has melted and run off by this time. It can snow at any time of year, but it never accumulates between the months of May and September, especially at lower altitude.