High pressure settles over the Western Alps for the next three days. Chamonix and Zermatt both stay dry, with valley highs near 26 degrees and barely any cloud. That is a rare rain-free window for a longer traverse. Start early. By midday the exposed sections bake, and under a clear sky the UV at 2,000 metres bites harder than the thermometer suggests. Carry more water than a cooler day would ask for.
Hydration packs ↗