Lingen an der Ems: 41.5 °C.
They have a nuclear powerplant there as well, I was there eight weeks ago during my 170km bicycle tour. The powerplant gets cooled from an artificial water reservoir build beside the nearby Dortmund-Ems-Channel, the biggest of its kind in whole Eurpope, a little ocean.

Last year, pedestrians told me, it already was dried down to less than half of its content, and since the basis is all concrete, it must heat up quickly as well. Possible that Lingen gets switched off as well.
I even filmed the reservoir during the tour. From 00:40:30 on:
Related map for that tour leg at 00:27:35