An outdoor enclosure for sulcata tortoises can provide them with enough space and natural sunlight to thrive. But in colder climates they will need a special habitat in their outdoor enclosure to keep warm. They are desert animals and should not be kept in climates where it snows, but they can tolerate the colder months when the outdoor temperature is in the 40s.
Outdoor sulcata tortoises will need two areas where they can stay cool and warm. The cool shelter should be slightly underground if possible. You can do this by propping up a wooden board with rocks and covering it with sand so the tortoises can crawl under it easily. This will help the tortoises hide from the sun when necessary. The second hiding area should be heated to keep the tortoises warm. You can construct a simple heated wooden shelter, similar to a dog house, with entrances for the tortoises.
A ceramic heater is the best choice for an outdoor sulcata tortoise enclosure. To keep the heat in, a flexible rubber material, such as pond liner, can be cut to make door-flaps. This allows the tortoise to crawl in while not allowing the heat to escape. The heater should keep the enclosure at least 70 degrees at night and maintain similar temperatures to a warm summer day if the weather cold. During the day, the tortoises need temperatures between 85 and 105 degrees.
Many people who keep their tortoises outside create a separate holding pen in their basement or garage when the outdoor temperature drops below 40 degrees. If you aren't sure if your climate is suitable to keep sulcata tortoises outdoors, you can create a separate enclosure inside. This indoor holding pen should have UVB lighting as the tortoises won't have access to natural sunlight, as well as additional heating similar to the outdoor shelter heating.
Cold Weather Safety
Because sulcata tortoises are cold-blooded, cooler temperatures will make them move slower or prevent them from moving at all. If the outdoor temperature is cold, it's a good idea to check over the enclosure to make sure the tortoises didn't fall asleep outside of their shelter before it got too cold for them to make it back on their own. If they are not all in their shelter, place them inside before they get too cold. Just because the heated habitat is there, doesn't mean the tortoises will use it when they should.