Wind is the worst - and there is NO such thing as a tailwind [except that this is created by the powerbar lunches....].
I commute year-around here in PDX,OR [15 miles give or take depending on the mood]. Including ice and snow and the rain and some hail...blah blah blah....and have ridden in temps from 106 F to 12 F. I cheat and keep to the hardtail for the winter riding [have yet to build up that cyclocross bike with disks]...
Hands are the hardest to me - below 20 degrees and I double layer a pair of moutaineering mitts over mid-weight REI riding gloves. For mid-20's and 30's I go with a set of weather resistant Performance heavy gloves.
Agree on the under 50's - knee protection. Be it knickers or tights over the rest. Wool clothing is popular here and readily available on-line [but somewhat pricey].
Go with thermal/poly tops of varying weights from REI [zipper necks for venting]. Light vest [Zephyr] for a chill or rain cape [gotta love Phil and Paul] for chill and rain. Around freezing and I add a micro fleece top. The head gets a doo rag all the year because I'm follically challenged and when it is mid-20's a turtle fur ear/head band thing.
Feet get the cheap $19 performance full booties for rain and cold. If it is snowy and in the teens - I actually add plastic bags inside the shoes over the socks to trap heat.
Also full fenders for the wet...
40's is nothing!