It's just not normal, planet is *ucked up. 64°C sounds unbelievable but I believe you! Concrete and tarmac accumulate heat day after day without cooling in the night and than just start radiating heat coming from the sun with no absorption at all.
Now me back to topic. Meteorologists say that the heatwave is over so I guess it will be another usually hot Hungarian GP but nothing extreme. I haven't checked the weather forecast but we just might have another wet race just last year since there was already one big shower that killed heatwave couple of days ago.