ERA5 2m temperature calculation

I'm having trouble reproducing the results being published in media and the ECMWF Twitter feed about the global average daily temperature:

Perhaps I am doing something wrong?

  1. I download a reanalysis of the 2m temperature from here for the last available day (July 3rd 2023):!/dataset/reanalysis-era5-single-levels
  2. I average it out with python and print out each hourly average in Celsius 

    input = NetCDFFile("")
    data = input.variables["t2m"]
    for hour in data:
        print( - 273.15) # convert K to C
  3. I expect that the averages would come close to the 16-17C that is being mentioned, yet my averages hover around 7-8C. I even plotted it with Panoply and am getting the same results

Am I using the wrong variable, or something else is a miss?

The ECMWF team helped me out here, I wasn't using weighted averages: