Anyone who has ever worn a poncho can attest to the fact that they are a cumbersome way to keep warm. I still haven't worn the one I purchased from Peru three years ago. Oops.
You'll be delighted to know that Shopbop has a collection of ponchos that are more convenient to cover up with. For instance, this VPL cashmere poncho allows you to freely wave your arms, whereas a more traditional kind with no armholes doesn't. It's your call. Poncho power!