Assuming it's 20C/68F in Chamonix (I wouldn't try to predict the Chamonix temp but let's use your 20C), you can expect the air temp to be about 35 degrees F at the top of the Aiguille. And because it's usually windy up there, it will feel even colder to you.It's the world's highest vertical ascent gondola ride and will take you 9300 vertical feet up from Chamonix to the top of the Aiguille, in 20 minutes. It gets my vote as world's most exciting gondola ride (but only if you're okay around extreme heights). For a little vicarious fun, click on the pic below and on the short video clip to give you an idea of the excitement!Click Here for PhotoThe video clip shows what it's like to go over the edge in the gondola on the way down--the video gets to the fun part at about the 10 second mark.Click Here for Video ClipDue to the foreshortening effect of the still photo, the actual scale is difficult to comprehend, until you're in the little gondola hanging 9000 feet above Chamonix, then you'll get it.Technical note for nerd engineers or accountants: (yes, I admit to being at least one of those :)Hey, how often do we get to do a math problem on the Helpline! We start with as assumption: that the weather rule of thumb, taught to pilots, will be fairly accurate on the day you go up, which is that the average temp decreases about 3.5 degrees F for every 1000 feet you go up. If it's 20C in Chamonix, that's 68F (20C/5*9+32=68F) & a 9300 foot increase in elevation means it will be ~ 9.3 x 3.5 degrees = 32 degrees F colder at the top, or approximately 68F minus 32 = ~ 35 or 36F.