The climate of Patagonia is well known for its strong temperament -sometimes really irascible- but we can say that splendid days, with clear blue skies and no wind are more frequent than his bad reputation suggests.
In general the climate in El Chaltén can be summarized in one word: "unpredictable".
The wind that sweeps away all in its way is a well known icon of Patagonia. It receives you with a memorable welcome as soon as you touch the ground when you leave the bus, when you reach a panoramic viewpoint and try to take a picture, when you go out for dinner after a nice shower... or at any time! The wind is an inescapable presence especially between October and March... but can be at any month of the year. You must know that in the austral summer -from 21st December to 20th March- days without wind are rare.
After a beautiful raising sun in a warm morning you can expect abrupt changes of temperature and the sudden appearance of dense cloudiness, intense rains and even snow hours later (of course it is possible that could happen the other way round). This situation is a characteristic that may take you by surprise when you go walking in the trails. For that reason you must always be prepared and take waterproof clothing with you at all times although the day appears splendid.
Another factor to consider is the solar radiation, wich in these southern latitudes is accentuated considerably, being strong even in cloudy days. For that reason we highly recommend to use solar protection for the skin, always.
Note that meteorological registries showed here were taken at ground level of El Chaltén, and as you go near valleys towards the West -to the mass of the South Ice Field- and win in height, the conditions are more and more humid and cold. In cold days it is possible that snow fall in the base campsites located at the foot of the hills while in El Chaltén only drizzles.
In the graph bellow you can observe that in the months of greater affluence of tourists -from October to April- the temperatures are mild, and in both months of high season -January and February- we can expect warm days; but do not take your warm clothes off because at night it can easily lower the temperature to 5°C (41°F) or less.
The average temperatures for January and February are:
• minimum: 7.5°C (45.5°F)
• medium: 13.3°C (56°F)
• maximum: 19°C (66.2°F)
If we took the meteorological registries from the last 15 years, we would observe great fluctuations between maximum and minimum temperatures and their occurrences along the year. Thus we have 19,0°C (66.2°F) of maximum temperature in February 1993, and an historical registry of 31,6°C (50.66°F) in February 2003. Or -5,5°C (°F) of minimum temperature in July 2003 and a historical registry of -20,0°C (-4°F) in July 2001.
Throughout the year, minimum and maximum average temperatures fluctuate considerably:
• lower registry: 1.83°C (35.29°F)
• higher registry: 23.40°C (74.12°F)
• lower registry: -8.37°C (16.93°F)
• higher registry: 10.37°C (50.66°F)
NOTE: The climatic registries from the last years have been provided by the Lago Viedma Department of the Los Glaciares National Park.