I intend to use an Arduino in an environment with highly variable weather. It will be an outdoor project staying outside during the entire year with temperatures ranging from a maximum high of approximately 37C (~100F) to a maximum low of approximately ~35C (-31F). It is unlikely that these temperatures will actually be reached, but it isn't unheard of. The temperature will most likely fluctuate between -15C (5F) and 30C (86F).
I have read that the ATmega32u4 and XBee 1mW U.FL (which I also intend to use) datasheets that both of these should operate properly between -40 and 85 degrees Celsius. Does this mean that the Arduino itself should be able to carry on normal operation? (if it runs a bit slow, that is fine, as long as it functions normally)
Also, I am concerned about condensation. I intend to use the following enclosure for the project http://www.adafruit.com/products/905 and will need to drill a few holes in it to get wires in and out. Will I get condensation in the enclosure? How big a problem is this? Is there an easy way to prevent it? Also, I'm curious whether the holes I drill for the cables will be problematic? Does anybody have any tips on sealing them?