late Feb (late austral summer) will result in a lot fewer people at Plaza de Mulas, the 14,000 ft base camp for the standard route.
Still, we had subzero deg F nights at 16,000 ("Camp" Canada 16,000, Camp Alaska 17,000, and Camp Berlin 19,500 and a few nights at each level acclimatizing or waiting for weather.
Acclimatization is an even bigger problem on Aconcagua compared to Whitney. If you are doing the grunt work yourself by carrying loads up and down and above the end of the mule line (14,000)
then three weeks door to door is in my opinion necessary to take all this into account. Two of us did it that way ,athough if you go with a guided group, they may plan for a faster itinerary.
Harvey
PS: Picture is of famous lenticular cloud "Viento Blanco" (white wind). We had a lot of that. Pretty much a hurricane on the top nearly every afternoon. Start early.
