As others have mentioned, an insulated nalgene bottle or thermos.

In winter I melt snow for water, storing in a cozied nalgene for a "while"
If I'm active (like snowshoeing along) I will often have a water bladder in my pack right
next to my back - this tends to get enough heat to stay liquid even in -30C,
although the hose and bite valve will freeze if there is any water kept in it. (you
can use an insulating sleeve on the hose for some protection for that)