During the night I was too hot to sleep.  What on earth?

I have one of those alarm clocks that shines the time and temperature onto the ceiling.

I woke up to see this

3:41AM
91 deg F

What?  Why is our house 91 degrees in the middle of winter?

I went downstairs to figure out what was going on.  Thermostat set at a cool 82 degrees.  Who did that?  Probably no one.

So...I didn't sleep most of the rest of the night.  Even with my windows open it never got below 80 for the rest of the night.  I know, because I could see it on the ceiling.