Isobutane is the fuel used in disposable lighters. The lighters' operation is dependent upon the butane's ability to vaporize and be ignited, and this depends somewhat upon the large pressure difference between the inside of the lighter and the atmospheric pressure outside the lighter. Assuming at atmospheric pressure of 1 atm, how cold does it have to be to keep your lighter from working?

At 27 C, vapor pressure is 2,775 torr and at -3 C it is 1050 torr.