You can buy a light which has a CR123 battery, which will handle cold/hot and sitting inactive much better than a Lith or alkaline battery light.
An example would be the SureFire G2X pro in yellow, $70, pushbutton (once for 15 lumen, again for 350 lumen), uses 2 CR123A batteries, 5.20 inches long.
Or, if you want a headlamp (to keep your hands free to change a tire, for example) then there is the Streamlight Sidewinder Compact $75, CR123 powered light.