Alps: a warm window before the cool-down

Chamonix reaches 28°C today under near-clear skies. Rain moves in on Sunday, and by Monday the high drops to 21. Zermatt cools harder still, from 23°C down to 16 across the same three days. Take the exposed ridges now. Anyone heading up midweek wants a shell and a warm layer packed, not just the kit that feels right this afternoon.