In the high area of that temperature range (~50F) then a standard AEG or, to a lesser degree, gas pistol will work fine.
For lower in the range, a spring bolt action is probably your best bet.
Otherwise, for a significantly larger cost anything powered by HPA (High Pressure Air) is what I'd recommend. If you're using a power source that isn't affected by cold temperatures (air, or a manually-actuated spring mechanism) then moving parts will be your largest concern, as they can become brittle and break easily in below-freezing temperatures. Therefore, Polarstar Fusion system HPA guns and 'BV' (bullet valve) classic airsoft guns would be ideal, as their power source is rarely affected adversely by cold temperatures, and they contain an extremely low number of moving parts. A standard 'blowback' gas airsoft gun could be easily adapted for HPA by replacing the magazine fill valve with an HPA fitting, but I wouldn't recommend it.
Prices for HPA guns start a ways above $500 for a Polarstar, and somewhere above $200 for a 'skirmishable' Classic, although the latter can be found much cheaper by sacrificing performance and, to a smaller degree, external quality.