Why water boils at 88 °C in La Paz, and what it does to cooking

Taste the Route, AI-assisted writing · 2026-10-30

Cook a dish where it comes from and the first surprise is often not an ingredient. In La Paz, at about 3,640 metres, a pot of water comes to a full rolling boil at roughly 88 °C [1]. It looks exactly like boiling at home, and it is twelve degrees cooler. Every dish that cooks in boiling water feels the difference, which is why cooks in high cities reach for lids, longer times and pressure cookers [4].

Why the boil gets cooler as you climb

Water boils when the pressure of its vapour equals the pressure of the air pressing down on it. Climb, and there is less air above the pot, so the water reaches that point at a lower temperature [4]. The standard model of the atmosphere gives the pressure at each height, and the Antoine equation gives the temperature at which water's vapour reaches it [2] [3].

Place	Height	Air pressure	Water boils at
Sea level	0 m	101.3 kPa	100.0 °C
Denver	1,609 m	83.4 kPa	94.7 °C
Mexico City	2,240 m	77.2 kPa	92.6 °C
Quito	2,850 m	71.5 kPa	90.5 °C
Cusco	3,399 m	66.6 kPa	88.7 °C
La Paz	3,640 m	64.6 kPa	87.9 °C
Everest base camp, south	5,364 m	51.4 kPa	82.1 °C

All figures are computed for a standard atmosphere [1]; on a given day the weather moves them by a degree or so. Near sea level the boil drops about one degree for every 300 metres [1], which matches the cooks' rule of thumb of about 1 °F for every 500 feet [4].

What it does to the food

A cooler boil means slower cooking for anything that cooks in water: food will take longer, and some dishes cannot be cooked the usual way at all [4]. Pasta and rice need longer and more water, because more evaporates over the longer time. Dried beans and tough cuts are where it hurts most, and where the pressure cooker earns its place: by sealing the pot it raises the pressure and with it the boiling point, back to sea level's or above [4].

Baking changes too, for a different reason. Lower air pressure lets gases expand more, so doughs and batters rise faster and can collapse, and liquids evaporate faster. High-altitude recipes adjust leavening, liquid and oven temperature for it [4]. A recipe written in Lima behaves differently in Cusco.

Nerd corner

The standard atmosphere gives the pressure at height h in metres as P = 101.325 × (1 − 2.25577 × 10⁻⁵ × h)^5.25588 kPa [2]. The Antoine equation for water between 1 and 100 °C is log₁₀(P in mmHg) = 8.07131 − 1730.63 / (233.426 + T) [3]; solving it for T gives the boiling point [1].

As a check, the Clausius–Clapeyron relation with water's heat of vaporisation, 40.66 kJ per mole, gives the same answers within half a degree: 87.6 °C for La Paz against 87.9 °C [1]. Both agree with the published standard-pressure table, which gives 89.8 °C at 3,048 metres; the formula above gives 89.9 °C [1] [4].

Check yourself

Does turning up the flame make boiling water hotter in La Paz? No. It boils faster and evaporates more, but it stays at about 88 °C, set by the air pressure [1] [4].

Why do pressure cookers help most at altitude? Sealing the pot raises the pressure inside, and with it the boiling point, back to sea level's 100 °C or above [4].

Roughly how much cooler is the boil in Denver than at the coast? About five degrees: 94.7 °C at 1,609 metres [1].

A notebook entry for tastetheroute.com, written with AI and checked by hand. Every boiling point is computed from the standard atmosphere and the Antoine equation, cross-checked by a second method and against the published table.