Looking at earth.nullschool.net on 13.09.2021
you can see that the temperature above the Himalayas appear warmer than the surroundings (at 700 hPa):
At the surface it looks more like one would expect with lower temperatures than the surroundings:
I'm guessing the explanation is connected to the difference in elevation. And that for some altitudes, temperatures closer to the surface (but not at the surface) are higher. Still, the same effect is not to be seen in other mountain areas in Europe and North America:
Any suggestions?