Depends on your location. In Wollongong it would be borderline, and only possible with very careful enclosure design and/or supplemental heat. I've known people who have done it further north. If you really wanted to put the effort into a really good enclosure it would certainly be possible. Some basic tips are having your pit/aviary with a north-facing aspect (against a north-facing wall or slope) and a carefully-positioned piece of glass can work wonders. If they can get under a piece of glass in a sheltered position, it works as a miniature hot house and you can achieve literally 80+ degrees even on cool but sunny winter days. In a large outdoor enclosure, you can have an easy time of providing a thermal gradient while still using these thermal tricks to make particular areas as hot as you want them.