How hot? So hot, that in Sachsen (Saxony), they had to limit on several older stretches of the Autobahn the maximum speed to 100km/h (62mph) and 120km/h (75 mph).
At high speeds the road becomes extremely hot which causes the surface to buckle and rip. The technical term for this type of damage is called "blow ups".
In 2013 and 2015, the blow ups at 34C temperatures caused serious damage of the Autobahn in Saxony and Bavaria, and even a motorcyclist's death.
This week, they expect in Germany record temperatures. The forecast for Wednesday is 40C (104F) which would make it hotter than in southern Europe.