Considering the Manquehue Hotel Santiago in Santiago?
A VT member wrote the following comment about visiting Santiago:
Santiago in Winter by kiwigal_1
The winter in Santiago is from June to August and last year (2007) got down around zero during winter and even snowed a little bit one day but generally it isn't really really cold. The mountains around it though are covered in snow and certainly this can affect bus travel between Santiago and Mendoza. The route is travelled frequently though and they clear it quite quickly.
The worst thing about Santiago in winter though is not the cold but the smog... there are days in Santiago that are called "pre-emergency" days when the school kids aren't allowed to do sports outside and there are big restrictions on vehicle use and log fires.