Chamonix and Zermatt: a dry weekend with chilly starts

No rain is forecast for Chamonix through Sunday, and valley highs climb from 19 to 21°C. Zermatt looks just as settled once this morning's fog lifts. The catch is the start of the day. On Saturday Zermatt sits near 7°C at dawn and passes 20°C by the afternoon. That is a 13-degree swing. Start in a light fleece, stuff it in your pack once the sun clears the ridge, and you won't carry a heavy jacket all day for nothing.