https://en.wikipedia.org/wiki/Foehn_wind
"WMO experts will now investigate whether the warm event recorded by Argentine scientists is a weather phenomenon known as foehn (föhn?). That is a common event in Alpine regions that often involves high winds at altitude and the rapid warming of air as it heads down slopes or peaks, driven by significant air pressure differences, the WMO said in a statement.
The WMO will also determine whether the temperature extreme is a new record for the entire Antarctic landmass. The Signy island in the Antarctic region, which includes everywhere south of 60 degrees latitude, recorded an all-time high temperature of 19.8 Celsius in January 1982. The average annual temperature ranges from about -10 Celsius on the Antarctic coast to -60 Celsius at the highest points of the interior.