Mexico City Weather in December: Official Averages and What to Pack

Mornings start cold, and a passing cold front can drop temperatures fast, so check the forecast again during the day, not only at breakfast. A HelloRoam Mexico City eSIM keeps your weather app and maps on mobile data while you're out in the city, with our support team on hand 24/7.

What shapes your packing is the daily swing. A December day here moves about 25°F (14°C) between dawn and mid-afternoon, so layers matter more than one heavy coat.

December averages 72°F by day and 47°F at dawn

The SMN, part of the National Water Commission (CONAGUA), publishes official 1991-2020 climate normals for Tacubaya, its observatory in the Miguel Hidalgo borough at 7,574 feet (2,309 m). The December figures look like this:

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The city's official visitor guide warns that winter nights and early mornings can drop close to freezing, and the record backs it up. The coldest December night at Tacubaya in those 30 years fell to 34°F (1.1°C). Rain is the rare event: even the wettest December in the period, 1995, brought only 1.8 inches (46.8 mm).

Afternoons are warm and dry, while dawn is cold and damp

Mexico City's Environment Department (SEDEMA) logs temperature and humidity every hour across its monitoring network and publishes the hourly weather readings as open data. Averaged across its 24 reporting stations for December 2023, 2024 and 2025, a typical day runs like this:

These figures come from many sites and only three recent winters, and they run a few degrees below the Tacubaya normals. The pattern is the useful part. Humidity peaks around sunrise and falls to about 33% between 2 and 4 PM, so afternoons feel dry rather than muggy.

Days are short. Through December the sun rises between about 6:54 and 7:10 AM and sets between about 5:57 and 6:09 PM, based on NOAA's solar calculator. That leaves about 11 hours of daylight for sightseeing.

Holiday dates from December 12 to January 6 fall in the dry season

Christmas in Mexico City looks like the rest of December: dry afternoons in the upper 60s or low 70s°F, then a quick cool-down after sunset, which comes at about 6:06 PM on December 25.

December 12 is the feast day of the Virgin of Guadalupe. The visitor guide notes that the Basilica of Guadalupe, in the north of the city, is the pilgrimage destination that day, and that fireworks can be heard across the city. The Christmas season then begins with the posadas, gatherings with family and friends held from December 16 to 24. If you stay into the new year, Día de Reyes (Three Kings Day) falls on January 6.

Cold fronts bring quick drops in temperature

A cold front, or frente frío, is the boundary where a mass of cold, dry air pushes into warmer air. The SMN's cold front tracker explains that once a front passes, winds usually turn to the west or northwest and the air temperature tends to fall. Its glossary describes those drops as rapid.

The SMN counts the fronts that enter Mexico each season. Its 2026-27 outlook, as of October 2, 2026, expects 9 in December, above the 1991-2020 average of 7. For the full September to May season it expects 56, against an average of 50. Those counts cover the whole country, not just the capital, and the SMN usually updates the outlook at its winter climate forum in November.

Check the SMN forecast in the days before you fly, and pack one extra warm layer if a front is on the way.

Pack layers for a 25°F swing between dawn and afternoon

A December wardrobe for Mexico City works best as layers you add and drop through the day:

• A warm jacket or fleece for early mornings and late evenings, when the station averages sit in the 40s and 50s°F.
• A T-shirt or light top underneath for the 2 to 4 PM window, when the same stations average 68°F.
• A sun hat and sunscreen. The visitor guide says direct sunlight can be intense at almost any time of year. SEDEMA adds that the city's altitude exposes it to about 20% more ultraviolet radiation than sea level.
• Covered-up clothes for the Basilica of Guadalupe. Its visitor rules bar shorts above the knee, tank tops, crop tops, low-cut tops, miniskirts and caps in its churches, chapels, museums and crypts. They also ask you to bring sunscreen, water and an umbrella for sun or rain, and they make a face mask mandatory indoors, so pack one if you plan to go inside.

Winter air carries more particle pollution

Clear, dry weather doesn't always mean clean air. SEDEMA says the city is prone to high pollution outside the June to September rainy season, and that in winter suspended particles reach the highest concentrations. Its ozone season usually starts later, in the second half of February.

SEDEMA posts its hourly air quality index, the Índice AIRE Y SALUD, with a risk level and advice for each reading. If you plan a long day outdoors, check it that morning.

December is a good month to visit if you plan for cold mornings

December is a good time to visit Mexico City if you want dry weather. It has the fewest rainy days of the year at Tacubaya, and its afternoons come within a degree of November's.

December and January are close to twins for temperature, though January gets more than twice as many rainy days. The trade-off in both is the cold start to each day. If you'd rather skip the cold mornings, the city's visitor guide points to spring (March to May). It suggests fall too, but the SMN normals still count about 18 rainy days at Tacubaya in September. Before you lock in dates, our guide on when to book flights to Mexico compares fares by season, city and airline.

Oaxaca and Cancun run warmer in December

If Mexico City is one stop on a longer trip, the SMN normals show how much December changes with altitude and the coast:

Oaxaca, southeast of the capital, keeps the dry winter but runs about 12°F warmer in the afternoon. Our travel guide covers getting to Oaxaca from the US, plus what to see and eat once you arrive.

Cancun is warm day and night but far from dry, with 3.8 inches of rain over about 12 days in an average December. The SMN normals put Cancun's driest months at February to April, with about 4 to 7 rainy days each.

Getting online when you land takes a few minutes of setup at home

Our Mexico plans connect to the Telcel and AT&T networks. They're data only, so your US number stays active on your main line, and calls over WhatsApp or FaceTime run on the eSIM's data. To choose a plan size, estimate how much data you need based on how long you use maps, calls and social apps each day.

Before you buy, confirm your phone works with eSIM. Then install the eSIM over Wi-Fi at home, and when you land, select the new line and turn on data roaming for it. Our eSIM setup steps for your phone show each screen.

If the trip goes on to Oaxaca or Cancun, keep the eSIM you set up for the capital. HelloRoam's Mexico City page sells our data plans for all of Mexico, not a city-only plan.

You may not need a travel plan at all. Verizon says all its Unlimited plans include talk, text and data in Mexico. The city also runs more than 35,000 free public Wi-Fi hotspots through its Internet for All program, though it warns that busy central spots fill up.