Western Alps: 16 degrees between dawn and afternoon

Zermatt sat at 11 degrees at half six this morning and climbs to nearly 27 by afternoon. Chamonix runs the same pattern, 16 to 28. That is a 16-degree swing on a dry, cloudless day. Pack for both ends: a light base layer you can hike in at dawn, and enough water for an afternoon that feels like July. From Saturday the peaks drop back to around 22 degrees, so this heat is a short window.