Mexico City has a mild, spring-like climate year-round, with average daytime highs between 21°C (70°F) in January and 26°C (79°F) in May. Sitting at roughly 2,240 meters (7,350 feet) above sea level in a highland valley, the city enjoys temperatures that would be far hotter at this tropical latitude if not for its extreme altitude. The result is a subtropical highland climate (classified as Cwb under the Köppen system) with two distinct seasons: a dry period from November through April and a rainy period from May through October.
Why Altitude Defines the Weather
Mexico City lies just south of the Tropic of Cancer, which means it receives strong, relatively consistent sunlight throughout the year. At sea level, this latitude produces hot, humid tropical conditions. But the city’s valley floor sits higher than many mountain peaks in Europe, and that elevation cools temperatures by roughly 13°C compared to what you’d feel at the coast. The thinner atmosphere at this height also retains less heat overnight, which is why nights can feel surprisingly cold even after a warm afternoon.
The valley is surrounded on three sides by mountains and volcanic peaks, creating a bowl-like geography that traps air and influences weather patterns. Morning temperatures cluster around 16°C (61°F) on a typical day, climbing into the low-to-mid 20s by afternoon before dropping again after sunset. This pattern holds remarkably steady for most of the year, giving the city its reputation for eternal spring.
Dry Season: November Through April
The dry season brings clear skies, low humidity (around 54% in January), and very little rainfall. Daytime highs range from about 21°C to 25°C (70°F to 77°F), making this the most comfortable stretch for being outdoors. The trade-off is nighttime cold. Lows regularly dip to around 5°C (41°F) during December and January, and frost is possible in the southern highlands. Layers are essential if you’re out after dark.
March through May marks the tail end of the dry season and is generally considered the best weather window. Highs push into the mid-to-upper 20s, rain is still rare, and humidity stays around 51%. May is the warmest month on average, with highs near 26°C (79°F), though that figure has been climbing in recent years.
Rainy Season: May Through October
Rain in Mexico City follows a predictable daily rhythm. Mornings are usually clear and sunny, with clouds building through the afternoon and heavy showers arriving in the late afternoon or evening. These bursts can be intense, sometimes flooding streets for an hour or two, but they rarely last all day. The southern and southwestern parts of the city, which sit at higher elevations with more forest cover, receive the heaviest rainfall, between 700 and 1,200 mm annually. The drier northern neighborhoods may see as little as 400 to 500 mm per year.
Temperatures during the rainy months are slightly cooler than the late dry season because cloud cover blocks some afternoon sun. Highs typically settle around 22°C to 24°C (72°F to 75°F). The combination of warmth and moisture makes vegetation lush, and the surrounding mountains turn visibly green.
Microclimates Across the City
Mexico City is not one uniform climate zone. Research has identified at least four distinct subregions shaped by elevation and how built-up the landscape is. The northern and eastern parts of the city sit at lower altitudes and are more densely urbanized. These areas tend to be hotter and drier, a pattern amplified by the urban heat island effect, where concrete and asphalt absorb and re-radiate heat. The southern districts, by contrast, climb into forested foothills and receive significantly more rain, with cooler average temperatures.
In practical terms, this means a neighborhood like Xochimilco in the south can feel noticeably cooler and damper than the Centro Histórico or areas near the airport in the northeast. The moisture gradient runs from northeast (driest) to southwest (wettest), and the temperature gradient roughly mirrors it. If you’re choosing where to stay, the central and western neighborhoods offer a middle ground between the two extremes.
Air Quality and Thermal Inversions
The same bowl-shaped valley that keeps temperatures mild also traps pollution. Mexico City’s geography limits airflow, and the thin atmosphere at 2,240 meters filters pollutants less efficiently than denser air at lower altitudes. Because the city sits at a tropical latitude where solar radiation is strong year-round, sunlight reacts with vehicle and industrial emissions to produce photochemical smog in every season, not just summer.
Winter brings the worst air quality days. Cold overnight temperatures can create thermal inversions, where a layer of warm air settles above the cooler valley floor and acts like a lid, preventing polluted air from dispersing. These events concentrate particulate matter and ozone near street level, sometimes triggering government advisories that restrict driving and outdoor activity. The rainy season generally offers the cleanest air, as afternoon storms wash particulates out of the atmosphere.
Recent Heat Records and Shifting Trends
Mexico City’s famously mild temperatures have been tested in recent years. In May 2024, thermometers peaked at 34.3°C (93.7°F), setting a new all-time record for the capital. That reading came during a broader heat wave that shattered records in ten Mexican cities simultaneously, straining the national power grid and causing blackouts. For a city where most homes historically didn’t need air conditioning, these extremes are a significant departure from the norm. The trend toward hotter dry-season peaks is consistent with both global warming and the intensifying urban heat island effect in a metropolitan area of over 21 million people.
The altitude also amplifies one less obvious consequence of heat: ultraviolet radiation. Thinner air means less UV filtering, so even on days when the temperature feels comfortable, sun exposure is more intense than it would be at the same temperature near sea level. Sunscreen matters here more than the thermometer might suggest.
What to Expect Month by Month
- December to February: Cool and dry. Daytime highs around 21°C to 23°C (70°F to 73°F), overnight lows near 5°C to 7°C (41°F to 45°F). Pack a warm jacket for evenings.
- March to May: Warm and dry, the most pleasant stretch. Highs reach 24°C to 26°C (75°F to 79°F) with minimal rain. Light layers work well.
- June to September: Warm mornings, rainy afternoons. Highs around 22°C to 24°C (72°F to 75°F). Bring a compact rain jacket or umbrella for the daily afternoon showers.
- October to November: Transitional. Rain tapers off, temperatures start cooling. A good window for fewer crowds and decent weather.