The heat has triggered forest fire alerts and is closing roads.
The federal government says there’s a major risk of fires across cantons Vaud, Geneva, Valais and Graubünden.
Open fires and barbeques are banned in the forests.
A road running between 2 villages in canton Aargau is closed as the road surface is melting.
The Rotbergstrasse is likely to stay closed for the rest of the month. Engineers say the soft surface means it’s too slippery.