I have the Castelli Meno Wind, which I really like. They are for -2°C - 8°C and windproof (their not waterproof but keep most light roadspray of).
I don’t think they have those anymore, but I think they are replaced with the Entrata Wind. Their Sorpasso is also similar but a litlle more waterproof as well.
I came here to second this one. I have had incredible success with all my GORE cold weather gear. Comfortable down into the teens Fahrenheit.
Personally I have a Gore WindStop sleeveless tank, and have coupled it with a Smartwool base layer, and PI AmFIB bib/tights. Yet even with that, I have on occasion run really hot. Dressing for riding in cold weather is such a mystery to me. I have done it and been perfectly warm and not sweating, and have done it and felt like a piece of meat trapped in a ziploc bag drenched in moisture from some unknown location. One race I did, I actually got to the point of wringing out my gloves because of the enormous amount of sweat pouring down my arms. My ‘kit’ was drenched, and I completely lost all control of my personal environment. I started frantically trying to control the sweating, but it got out of hand. Other riders were tossing their tops and also stopping to peel off other layers of their clothing. At some spots, the number of bottles was dwarfed by the articles of clothing.
Dressing for winter riding seems more art than science, and varies a lot depending on the person, and the temperatures and other environmental conditions. The second year I did that race I ended in better shape, but still had sweating, and it was raining that time too. Yikes…
That particular event was made worse because there were large road crossings that people queued up for waiting for the go ahead to cross, and the wait just sucked at riders fingers, toes, etc… (The next year, I missed, it was in the 60’s, and people were passing out because they overdressed. Wow)
Rapha Pro Team Thermal Shorts are more than fine down to 0 degrees C when combined with their merino base and long sleeve thermal jersey. Knee warmers could be beneficial if you’re riding Z1 or like long coffee stops…
Assos winter tights without insert/padding have been great for me. I like that I don’t need to purchase winter specific bibs and since it’s used over my summer bibs I can use the same one all week without washing after every ride. The price is also half of 1 bib so it really does provide a lot of flexibility for me.