January is already half over, so you would only have about two weeks until setting off on this hike, and you are so inexperienced that you do not know how to procure water while hiking? This is not a good start.

Yes, you are quite correct to fear hypothermia, especially in the February/March time frame you're considering. Hypothermia, along with falls and injuries, are the two most common reasons why hikers die.

As little as you would like to hear this, I would strongly counsel you to set aside all thought of attempting to do such a long hike right away and set your sights on an adventure that would allow you to gain experience without jeopardizing your safety. You should perhaps contemplate a car camping trip, taking day hikes and returning to your car and campsite each day. Such a trip could certainly give you all the challenge and satisfaction you could ask for. What you seek to do now is far too likely to end in failure, confusion and regret.