Mexico Geography, Climate & Nature

Mexico's geography is dominated by two major mountain ranges, the Sierra Madre Occidental and Sierra Madre Oriental, enclosing the high central plateau where Mexico City sits, at elevations often above 2,000 meters.

The country narrows toward the south into the Isthmus of Tehuantepec before widening into the Yucatán Peninsula, a low, flat limestone shelf riddled with underground rivers and cenotes rather than surface rivers.

Mexico sits on the Pacific Ring of Fire, giving it significant volcanic activity (including Popocatépetl, visible from Mexico City), while the long Baja California Peninsula adds an arid, desert landscape distinct from the tropical south.

Mexico's tropical latitude means temperature depends far more on elevation than on season -- the high central plateau, including Mexico City, stays mild year-round, while low-lying coastal regions stay consistently hot and humid.

Most of the country follows a wet/dry pattern -- a rainy season roughly June to September and a dry season the rest of the year, when most tourism peaks.

Northern Mexico has a more arid, desert climate, while the Yucatán and Gulf Coast see the country's most consistent heat and humidity, along with the highest hurricane exposure from June through November.

Mexico is one of the world's 17 megadiverse countries and ranks fourth in the world for biodiversity, holding 10 to 12 per cent of the world's species in a single country — over 200,000 of them. It ranks first in the world for reptiles, with 707 known species, second for mammals with 438, and fourth for both amphibians and flora, with 26,000 plant species. About 2,500 species are protected under Mexican law, across 34 biosphere reserves, 67 national parks and dozens of smaller protected categories.

The reason is geography. Two great mountain ranges, the Sierra Madre Oriental and the Sierra Madre Occidental, run the length of the country as the continuation of the Rocky Mountains, with the Sierra Madre del Sur crossing from Michoacán to Oaxaca, and the whole lot sits across the boundary between the temperate north and the tropical south. Mexico is where North American and Central American species meet, which is why a day's drive can change the habitat completely — desert to cloud forest to lowland jungle.

Three systems are internationally significant and all three are visitable. The overwintering forests of the eastern monarch butterfly population sit in the Trans-Mexican Volcanic Belt pine-oak forest on the Michoacán and State of Mexico border, 100 kilometres north-west of Mexico City. The Caribbean coast holds the reef, mangrove and cenote complex of Sian Kaʼan, a biosphere reserve from 1986 and a World Heritage Site from 1987, whose name in Yucatec Maya means the place where heaven begins. And the lagoons of the Baja California peninsula hold the gray whale calving grounds.

Climate change is already measurable here: protected areas are expected to face warming temperatures and reduced rainfall, which raises extinction risk for exactly the endemic species that make the country's biodiversity remarkable.

The two wildlife events most worth planning a trip around are both seasonal and both fixed. Monarch butterflies occupy a fraction of the 56,000-hectare Monarch Butterfly Biosphere Reserve from October to March; the reserve was designated in 1980 and became a World Heritage Site in 2008, and most of the overwintering monarchs of eastern North America are in it. Gray whales calve in the Baja lagoons in winter, alongside northern elephant seals, California sea lions and dolphins on the same coastline.

Mexico also holds two of the most precarious animals on earth, and they are worth knowing about for what they say about the country's conservation politics. The vaquita, a porpoise endemic to the northern Gulf of California with the smallest range of any cetacean, was estimated at 567 individuals in the first full survey in 1997, fewer than 19 by 2018, and a 2024 survey observed a minimum of 6 to 8 — the lowest ever counted. Monitoring in 2025 identified 7 to 10 individuals and the birth of new calves. The cause is bycatch in gillnets set illegally for totoaba, despite a partial gillnet ban in 2015 and a permanent exclusion zone from 2017.

The axolotl is the other, and it is the more remarkable because it lives inside the capital. It originally inhabited the interconnected lakes of the Valley of Mexico; the desiccation of those lakes was begun by the Aztecs and accelerated through the 20th century, and the area is now largely occupied by Mexico City. Wild axolotls survive in the canals of Xochimilco at somewhere between 50 and 1,000 adults, assessed as critically endangered, pushed to the edge by introduced tilapia and carp. The same drained lake bed that amplified the 1985 earthquake is the reason this animal is nearly gone.

Practically: choose a region and a season. Monarchs are winter, gray whales are winter, the reef is year-round but clearest outside hurricane season, and the tropical forests of the south are most active early in the morning at any time of year.