Mexico City sprawls across a high valley in the centre of the country at around 2,240 metres above sea level, ringed by mountains and volcanoes, at approximately 19.43°N, 99.13°W. Although it lies well within the tropics, its great altitude gives it a mild subtropical highland climate (Köppen Cwb) — spring-like temperatures year-round — where the year is divided not into hot and cold seasons but into a distinct dry season and a summer rainy season.

There is no hot summer in the lowland sense: the altitude keeps temperatures mild all year. The warmest, driest months come in spring, around April and May, before the rains, with highs around 26–27°C. Once the rainy season begins in late May, daytime highs actually drop a little, to around 23–25°C, as afternoon clouds and near-daily thunderstorms build over the valley, often clearing to bright mornings the next day.

There is no true winter either, but the dry season from November to April brings the coolest nights, with lows that can fall to around 5–47°C and occasionally to freezing on the clearest nights, sometimes with light frost on the city's outskirts, while days stay pleasantly warm around 21–23°C. The wide gap between mild days and chilly nights is a hallmark of the high-altitude climate, and Mexican homes are often built without heating.

Mexico City receives around 600–850 mm of rain a year, overwhelmingly concentrated in the wet season from June to September, when July and August are the wettest and rain falls as heavy late-afternoon and evening thunderstorms that can cause localised flooding. The dry season from November to April sees very little rain and abundant sunshine. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Mexico City's weather is governed by altitude rather than season, giving it an 'eternal spring' far milder than its tropical latitude would suggest, with a sharp daily swing between warm days and cool nights. The mountain-ringed basin that shelters the city also traps air, and combined with the thin high-altitude air this historically gave the metropolis serious smog problems, most pronounced in the calm, dry winter months.

To follow any single measurement in Mexico City more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.