For me it's year round as long as the humidity is low enough. Doesn't matter what season it is. I've done some more monitoring of my situation and I zap everything when the humidity is below more like 70% (rather than the 50% I estimated at first).

It's interesting that there's a rather equal distribution among the responses. Maybe I should have figured out a way to factor in climate and season.

Oh Herc, I meant to say I do that same thing to our poor cats! The youngest doesn't seem to mind, though.