Pre foot surgery, I ran outside year round in Chicago for several years. One thing I found frustrating was the difficulty of figuring out “how cold” it would feel on a given day. If it was 20 with sunshine and no wind, it would feel far lovelier than 40 degrees with horizontal rain. So I finally came up with the following which worked for me.
-In my mind the most important thing is avoiding getting wet, which will make a run miserable far quicker than just cold. So get a pair of lined gore-tex pants, and a thin waterproof shell/jacket.
-Running as low as single digits F, I never needed more than the lined pants on my legs. IMO, if your trunk and head were warm, your legs could be cooler. And it is no problem feeling a little cool when you start off - you will warm up quickly.
-Deciding whether or not to wear the pants was always a tough call, until I reached this decision. On my way to my locker-room, I passed a bank thermometer. I have no idea if it was accurate or not, but I decided if it was 40F or above, I HAD to run in shorts, and if 39F or below, I wore pants. Sure, there would be a day or 2 where my bare legs would feel chilly, but if my top was covered sufficiently it was never a problem. And if I felt chilly at the start of a run, I almost always warmed up shortly into it.
-For the top, I agree with a dry-fit bottom layer to avoid chafing. My preference was sleeveless tees - the same shirts I would wear to run in summer. The only things I needed other than that were a long-sleeved tee and a sweatshirt. Layering one or the other of those over my bottom layer and under the shell as needed would take me down to single digits in rain, snow, whatever.
-I RARELY felt the need for gloves. One the few occasions I would wear them, I would take them off during the run on all but the coldest days. The very thin stretchy ones they sell before marathons are great.
-For my head I had one old baseball cap, and one old knit cap.
I remember hearing something - I think it was from a Scandinavian cross-country skier but could certainly be wrong. They said, “There is no such thing as bad conditions, only bad equipment.” Get a couple of nice pieces of Gore-tex, and you can enjoy the outdoors in just about any weather!