make sure you have some pencils and paper. Pens will freeze

Another caution is that many "ball point" pens (although not called that much now) are almost impossible to use on paper that's even slightly damp even if only from high humidity or a few weeks in the vehicle. Although you can use body heat to thaw the ink by sticking them somewhere warm, a break in the internal ink column may still leave them unusable.

Some childrens' crayons often make a more reliable and more conspicuous marker to have onboard, although some of the recent "non-toxic" ones may be useless in adverse conditions. (Also applies to boating kits where the crayon wax can sometimes be handy for other things as well as for making marks.)

John