I would think if the water bottle isn't insulated but is inside your sleeping bag, that its temperature would eventually settle pretty close to your body temperature. How close would depend on how much clothing you were wearing and where the water was located. Something less than 98F, maybe in the 80s if it was close to your torso? That should feel moderately warm. Now, if it was in your foot pocket it would likely be cooler. But still, like was mentioned, it would still be warm to drink.
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