|Here in the Black Hills of South Dakota/Wyomong, USA, we have large swings in temp. Three days ago our temp was -5 f. Yesterday, it was 50+. I did not have any problems with expansion of rail, scenery or timber framework. This may be because my basement train room is insulated, heated and air conditioned. My Gn15 layout is built almost entirely on insulation foam. My HO urban layout is built almost entirely on the usual wood frame with plywood top board.
Insulating your layout space may help to keep the temps more uniform.