Water boils at lower temperatures at higher elevations.
Water boils at 100°C only at sea level (1 atm = 101.325 kPa). As altitude increases, atmospheric pressure decreases, and so does the boiling point — approximately 0.34°C per 100 meters of elevation. At Denver (1,600 m), water boils at 94.6°C. At the summit of Mount Everest (8,849 m), it boils at just 70°C — not hot enough to properly cook many foods. This affects cooking: pasta takes longer at altitude, eggs take longer to hard-boil, and baking requires recipe adjustments (less leavening, more liquid, higher temperatures). The relationship between pressure and boiling point is described by the Clausius-Clapeyron equation, which relates vapor pressure to temperature through the enthalpy of vaporization.