Clock Time Changes With Weather

I have noticed this winter that the New Haven, time only, clock on the living room wall seems to gain about 5 minutes per week.
The temperature in the room remains constant at about 70-72 degrees F. So, this leads me to wonder what the issue is that could cause this problem?
I fully understand that unlike pocket watches, a time only clock from the early 1900’s does not have a bimetal, temperature compensating mainspring.
Now what would lead to this issue that is different from the fall? After much thought I have decided to look at the humidity records for the room.
During the fall the humidity ran 48 – 55% RH. The humidity now is in the low 30% range 30 - 34% RH. This has caused a reduction in the friction
on the mainspring as the lubrication is less tacky. This takes into account that the mainspring lubrication is fresh and is fine.
So, to solve this issue you will need to up the humidity in the room and try to keep it more constant, (try for 50% RH) if possible.
Also, you will notice your personal comfort will be better with the increase in humidity.
I hope this may help a bit with this issue.

theoldclocks.com
Spencer Smith ---1/22/2024