I am now in West Michigan where for about 4 weeks it gets for sure cold in January/February. Weak car batteries show their faults kind of cold. 20 to sub zero temps with wind chills that are lower yet. Up to last December I worked outdoors, and am fairly hearty. No more, thank goodness!
As for cold temp kit, I had a hand knit wool sweater I picked up from Scotland, made in a little old lady's house (looked like a very nice old school cottage to me) back in the early 80's. Wore that thing for about 35 years. It was warm on the coldest of days, and warm yet cool on the chilly days. Worn with a wind shell it served me well. Insulated jeans worked well when on foot, but on the bicycle it was once again wool underwear with wind pants.
In the coldest conditions I had problems keeping the feet warm, mainly due to wind chill. Once I switched over to platform pedals the problem was solved because the shoes worn were insulated hiking shoes. Hands protected by any number of mittens and gloves, or combination of the two always worked.