|24||Polypropelene short sleeve undershirt|
|20||Add arm warmers|
|15||Polypropelene long sleeve undershirt & jersey, knee warmers & warm socks|
|10||Cycling jacket (or vest on top of above), full gloves, full longs, heavy wool socks|
|5||Add booties, warm long sleeve undershirt(s), warmer gloves and headband / hat|
|0||Warmer underlayers, booties & even warmer hat and gloves|
Things to also consider is how long you will be riding during the colder tempature. Is it supposed to warm up 5 – 10 degrees for most of the ride? How strong is the wind and what is the windchill supposed to be. As you pay more attention to what to wear you will no doubt learn what works best for you.