This is simply what I do, and others can chime in with different opinions.
I have had all my plumeria outside for the last month and only covered them when the temperature was predicted to get in the low 40's. If much lower than 40F I added strings of lights for some warmth. I haven't worried a bit about my plants with temperatures at or above 50F and I have seen absolutely no damage. My cuttings stay outside if the lows are above 50F and so far they have done fine as well.
