It's the morning dew which should be a concern or just moisture in the air. If it's housed inside the cabinet it may be ok but fans sucking in moisture if it rains will kill it. I have a shed that I thought I would place my miners in but I live where it rains a good part of the time.
Right, this is what I am concerned about aswell. But his point is that all the material inside the box will have a higher temperature than outside and therefore no need to worry about moisture building up. I kinda concur with him about this but I still fear moisture.