Does ambient air temp affect LTFT's?

My LTFT's were doing really well (between -5 and +5 percent) for the the longest time. Then, since it's been cold out (below freezing), I've notcied that my LTFT's are now way above/below 5% all of the sudden (without any fueling changes in my tune).

So is it normal for LTFT's to change due to cold temps (or temps in general)?

If not, what else may affect the fuel trims so much all of the sudden? I've noticed that at idle, they can be as much as 12% now... Strange...