How tight are your gloves/shoes and how hard do you grip the handlebars. The problem with hands and feet is that anything that is constricting the blood flow of your hand or feet will cause blood to leave the area and without the circulation of blood, your hands/feet will simply get cold. The winter riding elevates things cause typically we're wearing thicket socks, gloves, etc. I have two MTB shoes that I use to ride in, one being a half size larger because it is OK in the warmer months, I know my usual commuting shoes would be too tight and too constricting in the winter. Gripping the handlebars too tight also has the same effect, loss of blood, loss of warmth.

Jay