The graph below plots the average daily maximum temperature at all French GHCN stations in the northern hemisphere, for every summer day since 1895. The hottest day was July 28, 1947, which averaged 98F (37C.)
This year’s heatwave (so far) was nowhere near as hot as 2003, other than at a few stations along a narrow ten mile stretch in the south of France. We will have to see how the rest of the summer turns out.
I have been working on some new tools, which give me the ability to do some new types of analysis like this very quickly.