The normal climbing season lasts from November to March with January/February the most popular time, often with the best weather. Aconcagua is known for its storms, which can bring climbing to a halt with fierce winds, snow and low temperatures.
Wind chill rating: High
Camps: As far as Base Camp on the Normal (NW) Route your gear will probably be on a mule. For the 2 or 3 camps above that it will probably be on your back. This is equally true of the other 'normal' routes (e.g.Polish Glacier). So keeping the weight and bulk of your gear low without sacrificing performance is important.
Windchill can make this mountain a very hostile place. As well as your main clothing, make sure you have windproof mitts.