Mount Aconcagua, "The Colossus of America", so cold and special, so crude and dreamed of. It is precisely because of its weather that it is compared to the eight thousands of the Himalayas. The low humidity, low oxygen percentage and strong winds are only some of the most outstanding characteristics of the weather of Mount Aconcagua. The main cause of storms and bad weather is mainly the wet winds originated in the Pacific Anticyclone. The winds go South and rise to the West clashing against the mountain range, cooling and thus releasing their humidity as snow on the high peaks of the Andes.
Not only snow and wind-storms are common in Mount Aconcagua but also the feared electric storms, due to its geographical situation. Lightning bolts fall especially on the mountain peaks in the Northwest area and on the summit, making the stay and ascent difficult.
Mt Aconcagua is assailed by strong winds from the West (over 5500 meters above sea level), which added to the large size of the mountain, form the enormous and renowned "mushroom". It is located in the upper part of mount Aconcagua and can be seen from Plaza de Mulas, creating a beautiful scenery and a terrible negative forecast of strong winds and precipitation. Approaching the summit in that moment would be deadly. When a storm approaches it is advisable to abandon the upper part of the mountain.
Even in good weather (summer) the temperature at night above 5000 meters is about -20° C (-0,4º F). In the summit the usual temperature is -30° C (-22º F).
But in case of bad weather from the South, in Plaza de Mulas the temperature can drop to -18° C (-0,4º F), whereas in the altitude camps it is common to have -25° C (-13º F) Anyway most part of the day and night at 4200 meters (base camp), it is possible to wear short pants, whereas in the summit a simple polar jacket will do. This means the weather is not always so harsh. Climbers should be prepared, however, for sudden weather changes.
Mount Aconcagua is not visited in winter. The temperature there never goes beyond 0° C (32º F), besides being constantly lashed by strong winds and snowstorms. In the shadowy areas of the mountain the temperature is extremely low. Climbing the Mt. Aconcagua in winter would represent an exacting psycho-physical challenge which would require excellent equipment as well as much confidence and experience.