If it is something that you are considering please wait til warmer weather so that he/she can make a slow transition to outdoor life to give it time to acclimate to the temperature.
Again I don't recommend outdoor living for a bun, I truly feel they are happier and healthier living inside than out.
Rabbits do not tolerate extreme weather temperatures so you need to make sure their housing stays warm and comfortable and protects them from elements. Rabbits do not hibernate, so if your rabbit looks limp or sleepy and isn’t really reacting to anything then you need to get him/her to a vet ASAP!
If you have just got your rabbit and he/she has been kept indoors or is a baby, don’t put the rabbit outside until the weather get warmer (spring/summer), as the sharp change in weather can kill your rabbit.