Last week, Paris recorded its highest ever temperature. According to the data compiled for the past 150+ years, that is accurate. However, it does not acknowledge the fact that the temperature gauge being referenced failed to record the temperature on a similar hot day in 2003. It also ignores the impact of the Urban Heat Island effect.
The Royal Meteorological Society has recently published a long-term analysis of heatwaves (and cold spells) in Europe. This study suggests that the hottest years in Europe were in 1240 and 1474. Of course, no one had thermometers at the time to record the data from those years, either.