San Pedro de Atacama: how many days you need and when to go

How many days San Pedro needs

Three days is the floor and it is dictated by the excursions, which are half-day or full-day and cannot be combined freely: the Tatio geysers leave around four in the morning, the Valle de la Luna is a sunset trip, and the altiplano lagoons are a full day above four thousand metres.

Four days is right, and the reason is acclimatisation rather than sightseeing. Arriving and going straight up to the geysers or the lagoons is how people get altitude sickness. The sensible order is: arrive and do nothing, then the low excursions — Valle de la Luna, the salt flat — then the high ones. Five days lets you add the Rainbow Valley or the petroglyphs, or cross into Bolivia towards Uyuni, which many people do from here.

The altitude, which is the actual problem

The village sits at about twenty-four hundred metres and the excursions go far higher. The Tatio geysers are around forty-three hundred; the Miscanti and Miñiques lagoons about the same; the road to Bolivia crosses higher still. That is a serious gain in a short time, and altitude sickness here is common and occasionally severe.

The rules are simple and they work. Give yourself a day at village altitude before going high, drink far more water than feels necessary, go easy on alcohol for the first forty-eight hours, and take the high excursions slowly. Coca tea is offered everywhere and helps mildly. If you have flown in from Santiago at sea level, you have gone from zero to twenty-four hundred in two hours — treat it as such.

Anyone going on to Uyuni should know the crossing goes higher again, up to and above four thousand five hundred for extended periods. San Pedro is the acclimatisation stop for that trip, not a place to rush through on the way.

• El Tatio geysers — one of the world's highest geyser fields, at about forty-three hundred metres. Departure is around four in the morning; the steam only shows at dawn.
• Valle de la Luna — salt and clay formations fifteen minutes from the village, done at sunset. The easiest and one of the best.
• Salar de Atacama — the salt flat, with flamingos in the lagoons at Chaxa. Chile's largest, and a working lithium source.
• Altiplano lagoons — Miscanti and Miñiques, deep blue against ochre at four thousand metres. A full day and the highest thing most people do.
• Stargazing — the reason ALMA and other observatories are here. Tours run nightly except around the full moon.

The sky, and why it is the best in the world

The Atacama has the clearest skies on the planet and it is not a tourism claim: it combines almost no rainfall, very little water vapour, high altitude and near-zero light pollution, which is why the ALMA array and several other major observatories were built in this desert rather than anywhere else.

For a visitor that means an astronomy tour is not an optional extra but one of the two or three reasons to come. They run most nights and they do not run around the full moon, which washes the sky out — check the lunar calendar against your dates, because it is the difference between the Milky Way overhead and a bright grey sky. Bring more clothing than you think: the desert loses its heat completely after dark and these tours stand still for two hours.

What a hyper-arid desert is actually like

The Atacama is the driest non-polar desert on earth, and some weather stations here have never recorded rain. The landscape that produces is not sand dunes but salt crusts, clay, exposed rock and colour — reds, ochres, whites and the improbable blues of the lagoons. It photographs unlike anywhere else and it is why the region has stood in for Mars on film.

It also has consequences you feel. The air is extremely dry, the sun at this altitude is brutal, and the temperature swing between afternoon and night is enormous — shirtsleeves at four in the afternoon and near freezing before dawn on the same day. Sunscreen, a hat and lip balm are not optional, and every packing list here should include a proper warm layer regardless of the month.

The village, and the practical bits

San Pedro is small, low and built of adobe, with unpaved streets and a seventeenth-century church, and it is expensive by Chilean standards because everything has to be trucked in. Accommodation ranges from hostels to serious resorts; food is good and costs more than it would in Santiago.

Three practical points. Bring cash: cards are widely accepted now but ATMs in the village are few and have been known to run dry. Excursions are sold in the village and prices are similar — what varies is the guide and the group size, so ask about both rather than shopping on price alone. And getting here means flying to Calama, about an hour and a half away by road, and taking a transfer; there is no airport at San Pedro itself.

What to eat in San Pedro, and where

This is the altiplano rather than the Chilean coast, and the difference shows: llama instead of beef, quinoa that has been grown here for millennia, and Andean ingredients alongside the Chilean standards.

• Carne de llama

  What to order

  The meat that is not beef

  Lean red meat from an animal that has been herded on this plateau for thousands of years, served as steak or in a stew. It has very little fat, so it is cooked rare or slow and never in between, and it is what distinguishes a menu here from one on the Chilean coast. Try it once; it is the local part of the meal.

  Check it on Wikidata

• Quinoa

  What to order

  The grain that was always here

  A seed crop domesticated in the Andes thousands of years ago, grown on the altiplano long before it was a health-food export. In this region it is an everyday staple, not a trend, and it turns up in soups and salads rather than as a garnish. Eating it here is the opposite of eating it at home.

  Check it on Wikidata

• Pastel de choclo

  What to order

  The Chilean dish to order at lunch

  A pie of ground sweetcorn baked over a filling of beef, onion, olive and a hard-boiled egg, served in an earthenware dish with sugar scattered on top. The sweet-and-savoury combination is deliberate and it is the summer dish of Chile. In the desert it arrives at a table that is otherwise Andean, which is the point.

  Check it on Wikidata

• Empanada

  What to order

  What to take on a four-in-the-morning excursion

  A baked or fried pastry folded around meat, cheese or seafood and crimped shut, and the Chilean baked version with beef, onion, olive and egg is the standard. Every excursion here starts before dawn and these are what you take with you. Buy them the evening before; nothing opens at four.

  Check it on Wikidata

• Pisco sour

  What to order

  The drink, and the argument about it

  Grape brandy shaken with lime juice, sugar and egg white, and Chile and Peru both claim it, seriously and with legal filings. The Chilean version uses different grapes and is usually less sour. Go easy in the first days: at twenty-four hundred metres alcohol hits considerably harder than at sea level.

  Check it on Wikidata

When to go, and what each month costs you

The driest desert on earth has no wet and dry season in the usual sense. What governs the calendar here is the cold at night, which is severe at this altitude, and the Bolivian winter — summer thunderstorms in January and February that close roads.

• March and April

  Go now

  After the storms, before the cold

  The best window of the year. The summer storms have passed, the roads are open again, the nights are cold but not brutal and the crowds have gone home. Clear skies for stargazing and comfortable daytime temperatures. Prices come down from the January peak. If you can choose, choose this.

• October and November

  Go now

  Spring: warm days, clear skies, still quiet

  Warming up, dry, and ahead of both the summer storms and the holiday crowd. Nights are still cold but the days are the most comfortable of the year for excursions. Excellent for astronomy. Book around Chilean long weekends, which land in this window.

• September

  Worth it, but

  The end of winter, cold at night

  Days are pleasant and clear but nights are still very cold, and the four-in-the-morning geyser trip is genuinely freezing. Quiet and cheap, with excellent visibility. Fine if you pack for it; the temperature swing is at its widest now.

• May

  Worth it, but

  Autumn ending, winter arriving

  Cooling towards the winter cold, dry and clear, with few visitors and low prices. The days are still good and the nights are getting hard. A reasonable choice, and a step behind March and April on every measure except price.

• December

  Worth it, but

  Warm, and filling up before the storms

  Hot days, warmer nights than any other month, and the storms usually not yet arrived. The second half of the month brings the Chilean holiday season and prices to match. Good conditions with a rising crowd, and the last reliable window before January.

• January and February

  Think twice

  The Bolivian winter, and the Chilean holidays at once

  This is the counter-intuitive one: the desert's rain falls in summer. The altiplano gets afternoon thunderstorms, roads flood and close, the geyser trip and the high lagoons are cancelled at short notice, and the sky clouds over. It is also the Chilean summer holiday, so it is the most expensive and most crowded time of year. Worst of both.

• June, July and August

  Think twice

  Winter: the clearest skies and genuinely dangerous cold

  Dry and spectacularly clear, which is why astronomers like it — and nights that drop well below freezing, with the geysers at four thousand three hundred metres at dawn in temperatures that catch people out badly. Some excursions are curtailed. Come only with proper cold-weather gear and a reason.

Things that change the trip

• Give yourself a day at village altitude before going high. The geysers and the lagoons are above four thousand metres and altitude sickness here is common.
• Check the lunar calendar against your dates. Stargazing tours do not run around the full moon, and it is one of the main reasons to come.
• Avoid January and February. The desert's rain falls in summer: roads flood, the high excursions get cancelled, and it is peak Chilean holiday season too.
• Pack a warm layer whatever the month. The temperature swing between afternoon and dawn here is enormous, and every excursion starts in the dark.
• Bring cash. ATMs in the village are few and have been known to run dry, and everything is more expensive than in Santiago.
• Fly to Calama, not to San Pedro. There is no airport here; it is an hour and a half by road and a transfer is the normal way.