Weather in Santiago in December

A good month. December is a solid month to be in Santiago. Highs average 32.4 °C, lows 16.5 °C, and rain falls on 2 days — nothing in the month is working against you.

December ranks 10 of 12 — near the bottom of Santiago's year. September is the month that works, and the swing between the two is 28 points, which is a different holiday rather than a slightly better one. Worth keeping in perspective: December is the weakest month of Santiago's year and it is still a perfectly good one. The downside here is small.

Rain falls on only 2 days, so an itinerary with no wet-weather fallback is a reasonable risk. Pack for 32.4 °C days and 16.5 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 5 days clear 35 °C, so a serious heatwave is normal rather than notable; the day swings 15.9 °C from low to high, which means one bag has to cover both. Across the twenty years measured, the hottest December day reached 40.5 °C and the coldest night fell to 5.8 °C.

December is dependably dry, and that reliability is the point: across the twenty years measured, the wettest December on record still only managed 27 mm, and the driest managed 1 mm. There is no meaningful variability to plan around, which makes this one of the few months anywhere that you can build a fixed outdoor itinerary against without a fallback. The wettest single day in twenty years of Decembers brought 18 mm. Rain simply is not the variable that decides this trip — heat, crowds and cost are.

Wind is light at 7.8 km/h, so the temperature on the page is close to the temperature on your skin, and the air is dry at 30% humidity, which makes the heat far more bearable than the same figure somewhere humid — and dehydrates you faster than you expect.

How December sits in the year

Temperatures hold steady either side: 30.1 °C in November, 32.4 here, 33.7 in January. Nothing about the timing within the month matters much.

Daylight in December

December is at or near the longest days of Santiago's year: 14.3 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

An inland climate

With no coast nearby, the year swings a fair way — 26.3 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage. Within December itself the daily swing is 15.9 °C, so mornings and afternoons need different clothes.

How busy it gets

Quiet. Few other visitors, cheaper rooms, and a real chance some seasonal operators are shut.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

December in Santiago versus nearby

If Santiago is one option among several, the nearby comparison is worth making. Córdoba is the weaker option in December — within a degree on temperature, 10 days more rain. San Miguel de Tucumán is the weaker option in December — within a degree on temperature, 11 days more rain.

So: December is a compromise. September is 22 points better and is what Santiago is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Santiago

See all twelve months in Santiago, or where else to go in December.