We've yet to hit anything sub-25 this year, but this is the list.....a little colder and I might add lightweight long underwear on the bottom and heavier neck gaiter, but as long as it's dry and not too windy, I like the cold, dark mornings (11 mile ride to work) :

-smartwool midweight longsleeve, hi-viz REI jacket (heavy-ish, windproof, waterproof)
-wool buff, worn either as a double-layer beanie or as a neck gaiter/head cover combo
-normal shorts, swobo wool knee warmers, PI amfib tights
-heavy smartwool socks, MTB shoes, Endura mt500 shoe covers
-heavy sugoi gloves (firewall XT, I think)