Alps: a clear window before Monday's rain

Chamonix sat at 16.7°C at half six this morning under a clear sky and climbs to 27.7°C by afternoon. Zermatt does the same trick from 11.3°C up to 25.7°C. That is a 14-degree swing on a single walk. The dry spell is short: 3.8 mm of rain reaches Chamonix on Monday and 6.8 mm on Tuesday, while Zermatt's afternoon high slides to 19°C. Start early, and pack the layer you will only need on the way down.