I have caught it before in the winter time. That's how easy I can get it.I have been out in the woods several times and nobody warned me! Maybe poison ivy poses no danger in the cold season (?) - when i was dragged out of my cozy warm office to visit that frozen waterfall in Rochester NY, just as an example. - ATV on the frozen lake in Alberta, throwing buckets of boiling hot water into the freezing air of Illinois, making smores over a fire in Oklahoma… All done during the cold season.
However, the picture of that plant of horror is burned into my brain!