FYI temperature affects GBB's and GBBR's WAY more than it would ever affect an AEG.
From -5 to 30 degrees the only noticeable difference is in your battery life!
However, as I've learned myself, the minimum temperature you can oeprate most AEG's safely is -8 degrees. Any lower and your hopup gets too hard and tends to jam your first shot. This can lead to stripped piston!