It’s hard to say, since Antarctica is a polar region, so we can’t really know what a hot, sand desert climate would look like there on Earth. Perhaps the weather would be a little hotter in summer, and a little cooler in winter, but either way there are problems: if it’s summer at present, which is why they can run around barely dressed at night, then the characters really should be wearing more protection during the day; if it’s winter, on the other hand, and that’s why they can get naked during the day, then they should be freezing at night.
In any case, sun exposure remains the main issue.