Cold -> Heat. Basically nitro finishes aren't very flexible. Cold causes the wood to contract and the wood and finish contract at different rates. So if you take a guitar and leave it in the extreme cold for a while and then suddenly move it into a warm indoor environment the sudden contraction of the finish can cause this cracking - or "checking".
Actually, just the opposite. The warm environment causes expansion not contraction and the warmth causes the finish to be a little softer/more flexible. Going from a warm environment into a very cold environment causes the finish to become more brittle and to contract quicker than the wood which causes the finish to crack. But going back and forth several times is the key to creating a lot of checking.
I love the color and that the body has the belly cut and the forearm relief. All Teles should be made this way...way more comfortable to play than the typical slab.
Teles were originally designed as a slab because they were quick and cheap to make. When Leo designed the Strat, it was really an upgrade to the Tele in every respect. He really did it right with the Strat, which, after nearly 70 years, still remains basically the same.