What is the source of BB area creaking associated with ambient temperature changes?

A general answer would be welcome, maybe encompassing -10C-40C/15-100F temperatures, but my particular ride is an aluminium frame with pressfit BB30 and Tiagra commponents, in Scotland’s climate, stored outside but in a shed.

Last year I had a tiny bit of creaking/snapping from the bottom bracket/cranks, or at least it was at the same part of the pedal stroke each time. Through the winter when the temperature was generally 5-10C/40-50F it was pretty much silent, and this weekend it’s started making a lot of noise again after the temperature ranged from about 0-15C/32-60F in the space of a few days.

There’s not really anything else I can attribute the change to, I’m assuming there’s a small amount of expansion/contraction in the metal parts which may not be uniform across each component – last weekend no noise, this weekend Creak-Clunk City.