Here is Penny filling a balloon with helium.
And here we are launching the balloon from Halley V on a bit of a grey day.
Here is one of the first balloon launches from Halley VI.
Although the ground temperatures have not changed much over the last 50 years, the atmosphere above Halley has warmed significantly. Here is a graph from a scientific paper about the data from Balloons from this part of Antarctica - Significant Warming of the Antarctic Winter Troposphere, J. Turner, T. A. Lachlan-Cope, S. Colwell, G. J. Marshall, W. M. Connolley, Science 2006.