Probably the number one thing I forget to pack when fall, winter, and spring camping (and hiking) is my longjohns. I literally have like 10 pairs of longjohns, because I’ve had to go out and buy more pairs when I forget them and I’m a long ways from home.
Longjohns may seem silly. But they really do much to keep you warm. Yet, they aren’t something that’s normally visible to the public, and as such they are out of site and out of mind.
Yet, as soon as you get out in the woods, and start to have cold legs, you realize how nice it would be to pack your longjohns. Sure, one can get another cheap pair of cotton longjohns at any Walmart, but one would be better of it they just remembered to pack longjohns from the get go.
It’s always a good idea not to forget your longjohns!