Need a little more warmth under that helmet?
Or, perhaps you just want to look like a space alien?
Add a silk balaclava to your traveling apparel. It’s super light, quite comfortable and I especially wear mine when the thermometer heads south and many riders are not on their bikes.
You can get them made out of wool or other materials, should that be your preference. Another advantage of silk (besides the comfort and light weight) is its natural wicking properties, so it not only keeps you warmer when it’s cooler, it also keeps you cooler when it’s hotter. (Does that mean silk has a built-in thermostat?)