Dry spell in the Alps, cold starts to match

Chamonix and Zermatt sit under dry high pressure into the weekend: no rain in the three-day forecast, and Friday reaches 29 degrees in the Chamonix valley. The catch is the morning. Zermatt read 7 degrees at half six against a daytime high of 23. That is a 15-degree swing before lunch, so the light insulated layer you resent carrying at noon is the one you want on a seven o'clock start. Source: Open-Meteo, 3 September.