While I have only worked with gravid greens, I believe it would apply to yellows as well. I maintain a hot spot in the low 90's under about a third to a quarter of the cage floor area. The rest of the floor area has a gradient down to a cooler end that is at about 80. If the female is always on the warm area, then you should move the temp up slightly. The warmer basking area is critical, but it is just as important that they have a cool end to move onto when needed.

Kelly