Hi guys, i have to some parts for outside use and i live in an environment with extreme climate chamges, and im wondering what the best filament choice would be?
Probably ASA. Or a CF filament.
The “easy” answer is ASA since it’s the most UV resistant and rather tough. The not so easy answer is understanding what the parts are going to be used for and picking the filament to match that use case. Each filament type has their strengths and weaknesses, so it might be worth looking at each to help make that decision. Choose the right filament - 3D Filaments Guide for Bambu Lab Printers.
If a part won’t be in the sun very often, ABS would be a good choice since it would be a cheaper option than ASA. If you are looking for something that will stay strong and dimensionally accurate under heat and sun, you may want to use PC, though that will be much harder to print with. PA-CF filaments seem to be a popular choice, but they can absorb water and lose some of their stiffness.
You could even use PLA if the circumstances were just right 
An odd example is I have a cup holder I made for my wife’s Subaru that I made out of basic PLA as a test print with the intent to remake it out of ABS or ASA, but it’s actually survived for 2 years and still going. Even though PLA is the worst pick for printing parts that go in a car, in this instance it’s not really a bad option. It conforms to the shape of the cup holder and so it’s supported on all sides so is way less prone to warping due to heat. Knowing this, I can pretty confidently use PLA for similar scenarios which will be typically cheaper and easier to print than other materials.
I have holders made of PETG on my sunny balcony. There are no problems since 2021. But they hasn’t to carry much weight.