Katharina, I am glad you "butted in" as I don't have that much experience hiking in Switzerland - I am German and Switzerland is quite far for me.
But personally if it was me, I would try a different trail. If the weather is not cooperating, things can get really nasty in the Alps - much worse than in the Sierras. If you cannot change the date of your trip, I would change the APR for another, lower trail. There is so much great hiking in Switzerland that you can easily come up with an equally interesting, but lower trail. Maybe Katharina has some suggestion there. I loved the Jurahoehenweg.
All the best,