Originally Posted by Hiro11

"Chilly" might mean something different for you than it does for me, but for sub 20F I've found ski goggles or mountain biking goggles work well. Goggles with double-walled lenses prevent fogging very well and as the bottom is sealed work well with something covering your nose and mouth. I have a cheap pair of low profile enduro goggles and they are effective never fogging and with comfort on really cold (sub 20F) days. I have to admit I rarely use them as regular glasses with a hat under the helmet is more comfortable most of the time. Also, I personally don't like riding with something covering my mouth.

One tip: make sure the googles work with your helmet before buying. Also, don't buy ski helmets for cycling as they're way too hot.