Atacama altitude and best time to go

Where the Atacama is, and why it is dry

The Atacama is a desert strip about 1,600 kilometres long on the Pacific side of northern Chile, west of the Andes. It is the driest desert on earth outside the polar regions, and some of its weather stations have never recorded rain. The cause is a two-sided rain shadow: the Andes block moisture from the east, and the Chilean Coast Range blocks it from the Pacific. The tours in this guide are around San Pedro de Atacama, an oasis town roughly 100 km from Calama. High, dry and far from city lights, the region also hosts major observatories.

San Pedro's altitude, and what it means

San Pedro de Atacama lies at about 2,400 metres, and visitors there often feel mild altitude sickness, such as dizziness, tiredness and headaches. The US Centers for Disease Control and Prevention treats 8,000 feet, about 2,400 metres, as the height where altitude illness becomes a risk, so the town sits right at that line and the tours climb well past it. For the first 48 hours at that height, the CDC advises no alcohol and no heavy exercise. The table shows how high each stop is.

Pacing the high trips

Altitude illness shows up as headache, tiredness, loss of appetite, nausea or vomiting. The CDC says mild cases should pass within a couple of days, that you should not go higher until symptoms are gone, and that you should go down if they worsen at rest. It lists day trips to higher ground, sleeping lower, as one way to reduce risk, which is how the Atacama tours work. Chile's tourism board advises staying hydrated, avoiding heavy meals and moving calmly in the altiplano. The El Tatio tour is recommended for late in your stay. People with heart or lung disease, diabetes or pregnancy should talk to a doctor first, the CDC says.

Getting to San Pedro

Most visitors fly to El Loa Airport in Calama (code CJC). It has direct flights from Santiago, a flight of about two hours. From Calama to San Pedro it is about 100 km along paved Route 23, which Chile's tourism board puts at roughly 80 to 90 minutes. Public buses run from Calama to San Pedro, and airport transfers can be booked in advance, shared or private. Coming overland from Santiago is about 1,530 km and 22 hours of driving. If you take the El Tatio tour on your last day, the tourism board advises leaving your flight home for later in the day.

Read next: Atacama desert tours: which to book

When to go

Rain is rare, but the wetter months matter for tours. Chile's tourism board calls December to March the altiplanic winter, when humid air brings rain and high storms and routes to the main attractions may close. Check the forecast near your dates. From April the chance of rain falls to almost zero and skies are very clear, and the board names April to June as a good window, with fewer visitors than summer. Summer is busy, so book ahead. CONAF adds that Valle de la Luna trails sometimes close for sandstorms in winter or rain in summer. Winter nights are cold, which matters most for night tours.

What to wear and bring

Chile's tourism board advises layers, because temperatures can drop below zero despite the intense midday sun. A day can run from a freezing start at El Tatio to strong sun by midday, so wear a T-shirt under warm layers you can take off. Tour notes list a windbreaker, warm clothing, hiking or comfortable shoes, a sun hat, sunglasses, sunscreen and water. The full-day lagoons tour also asks for your passport or ID card and some cash. Drones are not allowed, and CONAF bans them in the reserve without authorisation. The El Tatio and Valle de la Luna tours also list alcohol as not allowed.

Language, length and pickup

Tour lengths differ: about ten hours for the full-day lagoons route, around six for El Tatio, four for Valle de la Luna and two and a half for stargazing. Guide languages differ too. The lagoons day offers Spanish, English and Portuguese, El Tatio and Valle de la Luna list Spanish and English, stargazing adds Italian and German, and the four-day Uyuni crossing lists Spanish only. None listed French or Dutch when checked, so ask before booking if that matters. Pickup covers hotels in San Pedro's town area. The El Tatio and stargazing tours do not collect from the outlying ayllus such as Quitor or Yaye.

Children, health and access

Age limits differ by tour: El Tatio excludes children under 9, Valle de la Luna under 8 and stargazing under 4. The full-day lagoons tour and Valle de la Luna list wheelchair users or people with mobility impairments as not suitable, and the lagoons tour also lists heart problems and high blood pressure. The valley's own trails are rated easy to moderate by CONAF, with the Duna Mayor walk at 45 to 60 minutes. The Miscanti lagoon trail is rated medium and takes about 90 minutes, with altitude named as a risk. Read each tour's not-suitable line before you book.

What the geysers and lagoons are like

At El Tatio the geyser fountains average only about 75 centimetres high. Minor eruptions come roughly every dozen minutes and major ones every few hours, so the show is many vents steaming in cold air. The ground around them can be thin over boiling water. At the lagoons and salt flat, CONAF lists vicuñas, foxes and flamingos among the wildlife. The Salar de Atacama has a rough, crusted surface, unlike Bolivia's smoother Salar de Uyuni.

Read next: Salar de Atacama's flamingos and altiplanic lagoons

Who this isn't for

If you cannot spare a night or two to adjust, or you have a heart or lung condition, high blood pressure or a pregnancy, the high tours may not suit you, so ask a doctor first. If you dislike early starts, El Tatio is not for you, because tours leave in the dark for the cold-air steam. If you expect tall Yellowstone-style jets, El Tatio will disappoint, as its fountains are small. And if you need a wheelchair-accessible day, check each tour's own notes, because several list it as unsuitable.