In my experience PETG can be used outdoors without problem.
I am actually right now printing a small series of parts in black PETG that are going to be used in a marine buoy.
PETG does this at least as well as ABS in my experience. ABS generally can withstand a bit higher temperatures, but for many applications PET(G) works just as well. And if the parts are think or small, PETG often performs better because it has a little better layer adhesion.