Transmission fluid: whats too hot or too cold

[nujac]

I recently installed a transmission temperature fluid guage right before the fluid enters the after market transmission cooler. I am not running the fluid through the raditor to help deal with the +100 degree weather in south Texas. We do however have near desert weather where it is 30 degrees in the mornings in 80 degrees in the afternoons in the winter. My transmission fluid temperature reading leaving the transmission before being cooled stays at around 110 degrees when the outside temperature is in the 40s. When the outside temperture is in the 80s the fluid temperature is around 130 degrees on the highway and 160 degrees in town. I do not know what it will be when the weather is in the 100s.
Can transmission fluid be too cool and harm a transmission? And how hot can it get before it becomes a problem?