An increase in air pressure increases the boiling point ; a decrease decreases the boiling point . In the low pressure environment at the top of Mt Everest for example , water boils at only 69 Â C. ( 156.2 Â F ) . On top of Mount Everest , at 8,848 m elevation , the pressure is about 260 mbar ( 26.39 kPa ) and the boiling point of water is 69 Â C. ( 156.2 Â F ) .