Yeah, I get that. Same thing happened to me between 1st and 2nd TM. Difference in performance was staggering. You're going to ace this, as long as you avoid hypothermia.
The thing about the cold weather events is that they force you to tap into other areas of mental and physical strength to make it through. Makes it for a much more fulfilling experience once its over and afterwards in terms of knowing what you can and can't deal with.
Everyone is a superstar in the gym when its warm, fresh, clean, and you are not up for 24 hours straight and tired and hungry. Cold Wet and Tired will humble anyone - I don't care how big tough and jacked anyone thinks they are.