Alpine high pressure: dress for a big swing

A stable high sits over the western Alps this week. In Chamonix, mornings start near 11°C and afternoons climb past 23°C, with dry skies forecast for the next three days. That is a swing of more than ten degrees. Begin in a light insulating layer, then strip back to merino as the sun gets to work. Zermatt runs cooler, around 9°C at dawn. Pack a windproof shell for the ridgelines and both ends of the day are covered.