I agree that even if the charts that we have seen today verified, we would probably not see 40C being breached due to cloud cover from thunderstorms that would be spawned in the heat, and the fact that it is only a one day occurance and doesn't have much time to set in. However, it does serve as a reminder that all of the ingredients necessary for those sort of temperatures to be breached are possible, all they have to do is happen at the same time ad it could happen.
I don't think it will happen any time soon, but I think it definitely could happen sometime in the near-ish future.