Climate varies according to altitude. Coastal areas and lowlands (tierra caliente) are hot and steamy with high humidity, while the central plateau is temperate even in winter. The climate of the inland highlands is mostly mild, but sharp changes in temperatures occur between day and night. The cold lands (tierra fría) lie above 2000m (6600ft). Rainfall varies greatly from region to region.

Only the Sierra Madre Oriental, the Isthmus of Tehuantepec and the state of Chiapas in the far south receive any appreciable amount of rain during the year, with the wet season running between June and September. All other areas have rainless seasons, while the northern and central areas of the central plateau are dry and arid. There is some snow in the north in winter. The dry season runs from October to May.