I'm in Florida, so, I can't comment on the freezing part, but I just purchased a North Face Neutron 32. It has a seperate compartment for a 2L Nalgene hydration bladder, mine is on order. The bag has alot of versitility for a daypack. It has numerous external attachment points including a front bungee system, a "platform" for a bike helmet, tool hangers, 2 water bottle mesh pockets, an internal organizer, a main storage area, and the seperate compartment for the Nalgene bottle.

Right now it has 4 books (about 5 inches total), my North Face rain gear, hat, sunglasses, wallet, cellphone and still some room for an extra pair of shoes on the outside. It is probably only 50% loaded, but for a day trip of anything, I think it would be good. I paid about $100 for it. The bladder was another $30.