I've got one outside, hanging out of the window (via a CD rom audio cable to plug it into) but I encapsulated it in a white diffused plastic 135 film canister, with self-amalgamating tape to cover the slot I cut in the lid to get the cable through. It needs a certain amount of weatherproofing, but the position mine is in can get sun shining on it (on those odd days) and that gives rise to over-reading.