I'm frequently tooling around on the scooter in a T-shirt in 16-degree weather (well, as frequently as it gets down to 16 degrees, which isn't nearly frequent enough). Feels good man! Not in shorts, though...don't want the hairy legs causing distracted drivers.
I sure the hell wish the cold felt colder. Can't even remember the last time I actually felt cold in Taiwan. Some time in the late 1990s probably. Maybe I need to move to Jade Mountain.