It sounds stupid - I know. Arm warmers. Why not just wear a jacket like the rest of us? The advantage of these which I discovered not too long ago is that they can be bundled up and stuffed into your jersey. Unlike a jacket that weighs a lot and is bulky, arm warmers are much more convenient to put away when not in use.
It blends right into the color scheme! Canari had the only two toned arm warmers I've ever seen available online or in a store. They're designed very well. Rubber in the upper sleeve holds it in place. The seams are all of high quality.
I found out the hard way of the disadvantages of a jacket. It was cold in the morning so I wouldn't have left the house without a long sleeve. Later that day it was too hot to keep on. My jacket had removable sleeves and even trying to stuff the sleeves (while wearing the vest part of the jacket) into my bag was a task. These are small enough to fit in the jersey pocket!