Outdoor chams won't need a UV light even on cloudy days. But a cham kept near a window screen will.
There are feral populations of both veileds and Jacksons in SoCal, so both species can be kept outdoors. The key is that your cage placement will vary depending on which species you keep. The feral chams can choose where they want to be in the environment, but your caged chams can't. So it's not really as simple as just picking any old space for your outdoor cage placement. You'll have to familiarize yourself with each species' requirements and then decide if you have what it takes to provide them in your yard. Some things to consider (this is just a random list):
1. How much sun does the spot get in the morning, midday, afternoon? This is probably the most important thing.
2. What about airflow and the surrounding environment? An enclosure up against a stucco wall is going to heat up a lot more than a cage that's nestled into bushes and trees. Also, consider how much person traffic or pet traffic will go near the cage - chams don't like constant interruptions.
3. What about cham safety? From both animals and people. Raccoons, possums, cats, and birds are all dangerous cham predators. So you're going to have to make your cage predator-proof. Also, make sure your cage is not visible to people who might want to steal a new pet. A good place to get ideas for predator-proof cages is to look up how people have made their chicken coops raccoon or fox-proof.
4. What about water? Don't build your cage in an area that's too far from any water spigots. I learned that one the hard way
5. Bigger is better. The more space you have, the more opportunity you have to create 'microhabitats' for your chams. They'll be better able to find a spot in the enclosure that is right for them: like lower down in the plants when it's hot out, or higher up on a basking branch when it's cooler.
6. Other random things I encountered: escape, wasps nests (which can look like a tasty snack to chams), feral chams fighting or trying to mate with my chams, etc.