From the description it could be protein buildup
But it could very well be that you just need to use a heavier conditoner. It's not that cold here in South Carolina either but on the dry days I swear I nearly have to use a dT just to get my hair to look normal. And my hairs not dry or damaged either.
Low porosity, medium texture.

If it smells good put it in your hair, if it tastes good spit it out!