In terms of outdoors housing, obviously you need something that is sturdy. Your main concerns are you bunnies digging out, or predators getting in. So if you have a run or hutch on lawn or dirt, you’ll need it to have a wire bottom so that they can’t dig out, this also prevents foxes etc digging in. I’ve seen many set ups with a big wooden two story hutch as the main home, with a run attached onto it that the rabbits are let out to in the day time. The run also needs to have a roof on it, whether it’s wire, or partially shaded to prevent them jumping out and again with the predators. Location is also a concern, you don’t want the hutch in the sun in the heat of the day because it will heat up and rabbits overheat easily. Cold is less of an issue. I would think that an inbetween season such as spring or autumn would be the best time to transition to outdoor living as the temperature extremes and fluctuations are less.
Otherwise, depending on where you live there are more concerns for diseases from biting insects, and the risk of fly strike, but hutches can be insect proofed using fly screen to prevent bugs getting in.