Originally Posted by dmhpilot

A little secret:

All VNAV paths are curved. This is why there are temperature limits. The curve (because all GPS satellite orbits are a curve when considered two dimensionally) is negligible on a standard day but steepens on a hotter day and shallows on a cooler day.

Once you go past the approved temperature limits, the curve is either too steep or too shallow to make a safe transition to landing at the DA/MDA.