This is what I have found over this winter living in Denver where we have temp swings from -10 to +60 over the span of a couple of days.
This is with a Flea and a Kala Laminate Soprano, so far other than the going out of tune when left in the car at work there have been no problems.
The cold will make the wood shrink enough that the tuning drops flat some times even a whole step (I tuned the Kala at work lastnight the "C string" this morning had dropped to "B" and that was overnight in my basement where its 58deg and work is 70 deg), but it seems that my body heat will also swell the wood to make the tuning go alittle sharp too.
The Flea will go WAY out of tune but I would think that has to do with the friction tuners slipping as the wood shrinks.
Now I wouldn't be leaving my KoAloha in the freezing car but just going from the house to the car and back with it in its case I have no problem with.