that's kinda the PITA with the AZT. you might spend Monday at 2,300 feet in a valley, then Tuesday at 8,600 feet at manning camp. I have 2 sleeping bags (quilts) but supplement my 35° quilt with down jacket and pants, if I know it will be colder. for me, even worse than being cold, (which I control w/ method mentioned above) is being too hot in a bag that doesn't vent well. I guess that's the bonus for sleeping with quilts. YMMV.