Apr 30, 2017 - 11:21 PM
Salzburg has a reputation for being wet, so good rain gear including waterproof shoes are essential. I've been there in both summer and winter and spent a lot of the time under an umberella. From memory, Garmisch is higher than either Innsbruck or Salzburg and should be a bit colder.
Snow fall is not dependant on the temperature at ground level, but at cloud level. Temperature decreases 1 Deg C for every 100 mtrs of altitude, so it is entirely possible to get snow showers in the valleys when conditions at altitude are right. Grindelwald had string of sunny days last month, the crocuces had bloomed, then last week got 40 cms of snow overnight. Mountains make their own weather.