Record-breaking heatwaves have dominated the news recently
In a system with natural variance around the mean then the longer the record of that variance the larger the record deviances from it.
3 sigma events happen more rarely than 2 sigma. But keep records for long enough and you’ll have a 3. And a 4 etc.
We’ve been – accurately – recording temperature for a century or three – dependent upon your definition of accuracy – so one and three century records should be appearing.