Be mindful that your air compressor is susceptible to extreme cold conditions and rain. Exposing it to the elements can cause irreparable damage even though it drastically reduces the volume levels inside.
Sunlight is another factor that affects the performance of the compressor. If it overheats in direct sunlight, it could be catastrophic for the machine and you. The best advice is that if you are going to install your air compressor outside, make sure you cover it to keep it away from snow, rain, and sunlight, and you insulate it from extreme temperature swings.
Oh, and be prepared to increase your maintenance schedule to keep it in good working order.