Besides all the good advice you will get re base layers you might also think about another strategy.
If you wear over-pants over your street pants
Well, I don't wear pants at all when riding. That is, I don't wear pants or jeans under my motorcycling pants, which are a not-great Joe Rocket Ballistic something or other 10.0
Where I get fancy is with the base layers. I have polyester fleece, polyester micro-fibre, silk and my latest purchase, 200 gram merino wool. They all work. If it's really cold I'll put rain/wind pants over the Joe Rockets and two base layers under.
Top is the same sort of base layer, electric Gerbing heated jacket liner directly over the base layer, all under the Joe Rocket jacket. Add a fleece jacket over the liner and a wind/rain layer over all when even colder or wet.
I don't use the waterproof liner for the Joe Rocket suit anymore. Rain gear on the outside makes much more sense. I suffered a mild but definite and potentially dangerous case of hypothermia a year ago when I got quite soaked on my bike in cold weather, and was lucky and smart enough to find and stop at the first motel. I don't intend to get that numbingly cold ever again.
My current favourite base layer is the Icebreaker New Zealand merino wool, an excellent old-school technical layer. An ex girl-friend looked kinda sexy in her merino wool under outfit. My own outfit might garner comments as well, but sexy would not be one of the words used, I think.
I like jeans btw, but they have no place under motorcycling pants. For me anyway.
My latest purchase is a favourite as well, a merino wool neck warmer (tube), similar to this
. I don't have this particular model, but the same idea. Better and more versatile than than any scarf I have ever worn.
Yeah, staying warm is cool.