Ahh. My nights never had it drop below ~-350. So it must be server-side after all, if damage is being applied.
I've never received damage in the morning from this bug. What is your test environment?
After a little further testing, it doesn't appear to affect single-player. Added a screenshot as requested.
Ahh. My nights never had it drop below ~-350. So it must be server-side after all, if damage is being applied.