A bit of rain, no but generally yes; it has no water resistance, which means that you can not wash it or stick it in a dishwasher..
also remember it has a pen that may not appreciate getting wet.
Realistically:
I would guess that if you get it wet and then dry it quickly then you should get away with it, but I would not try it with mine.
I have washed USB sticks and phones, accidentally, in the washing machine and as long as I took them apart immediately, rinsed them and stuck them out in the sun they came out fine.