Alps: a wet start, then two dry days

Chamonix takes the brunt today, with around 32 millimetres of rain before the front clears. Then it settles. Two dry days climbing towards 22 degrees. The catch is the nights: Zermatt drops to 6 degrees after dark, a wide swing from the afternoon warmth. Pack for both ends. A merino base layer covers the cold dawn without weighing down the midday climb.