I try to remember to take a sip every 10-15 minutes because I know I'm very good at just ignoring thirst I am until I start to feel the effects of dehydration. In summer, I always make sure I drink 500ml an hour, but I don't worry if it drops back to half that in winter.
I remember really not wanting to drink on early winter commutes in the UK because I was already cold without adding even colder liquid to my body, so I waited until I got to work, and then had a cup of tea/coffee to rehydrate and warm me. If I was cycling in cold conditions now, I think I'd get an insulated bottle and take a hot drink with me. The added warming effect would give me extra incentive to drink frequently.