Just hold that steady, please

I was looking at the swans on the canal on my way home today and noticed this one preening itself. Eventually, when I'd almost given up hope of getting a good blip (and my right hand was freezing cold) it open it's wings. I was so pleased and surprised, I think I shook the camera a bit, so this is far from perfect, but more interesting than the preening pose.

Why does it feel do much colder today?