Is Mexico really a hot country?

Referees often ask me what the international relevance is of studying the effects of temperature and climate change in Mexico when it is such a hot country (aka external validity).

These maps are my answer. Mexico is not the hot desert Hollywood shows us. Some 28% of the territory averages below 18 °C and only 21% above 24 °C. Height above sea level explains 81% of the differences in temperature across the country, and half of the territory lies above 1,000 metres.

The distribution of rainfall is also quite uneven. In an average year, 14% of the territory gets less than 250 millimetres (about 10 inches) and another 14% gets more than 1,500. The wettest quarter of the country receives 51% of all the rain. The driest half receives 23%.

The third map shows both at once. In a single country there are 50,000 km² (about 1.2 times the size of Switzerland) with temperature and precipitation similar to those of Phoenix, 26,000 to those of Paris, and 65,000 to those of Hong Kong (within 1.5 °C and 20% of the rainfall).

The data are ERA5-Land, a reanalysis that combines measurements with a climate model, at about 11 km of detail. They are not direct station readings. The two-variable map follows an idea by Milos Popovic for the Iberian peninsula.