The low humidity, the low percentages of oxygen, and the strong winds are just some of the most wonder characteristics of the climate of this hill. The leading causes of storms and those responsible for bad weather are fundamentally the humid winds expelled by the Anticyclone of the Pacific, which run towards the South and rise towards the West, colliding with the mountainous mass of the Cordillera, cooling and where its humidity becomes snow on the high peaks of the Andes. On Aconcagua, there are storms of snow and wind, and due to its geographical location, the most feared storms are electrical storms. The mountain ridges (the northwest sector and the top) are most visited by electrical sparks (lightning), making it challenging to stay and climb.
In the Aconcagua Expeditions , strong winds blow from the West (at more than 5500 meters above sea level) that, added to the great size of the hill, form the giant and famous mushroom. This is located in the upper part of Aconcagua and can be seen from Plaza de Mulas, creating a beautiful landscape and a terrible negative forecast of strong winds and high rainfall. Approaching or entering at such times would be deadly. When coming it is advisable to leave the top of the mountain.
Even with good weather (in summer), temperatures of –20 ° C (–0.4 ° F) are recorded at night above 5000 masl. At the top, the standard temperature is –30 ° C (–22 ° F).
But when the Aconcagua climb is visited by bad weather and by air masses from the South, Plaza de Mulas maintains an approximate temperature of –18 ° C (–0.4 ° F). In comparison, it is common in high-altitude camps to have –25 ° C (–13 ° F). Likewise, most of the nights and days at 4200 meters above sea level (base camp), you can be in shorts, while at the top you can get to be with a simple fleece; these points are the exact reference that sometimes the climate is not so harsh and harsh.
Conveniently, the mountaineer is always prepared for these sudden climatic changes. During the winter, Aconcagua is not visited. Its temperature never rises above 0 ° C (32 ° F), in addition to being hit by strong winds and constant snowstorms. Shallow temperatures are recorded in shady places on the mountain. Climbing Aconcagua in winter would be a significant psychophysical test, and for that, you need a good team, as well as a lot of confidence and experience.