0.28 °C,plus minus a small error, as the sum of the 2009-2008 temperature differences averaged over the known days (Dec 1st - Dec 17th), plus the known final December 2008 anomaly (0.18 °C) - an algorithm that had previously been proven very successful.
You might have said that it was a bold prediction because the figure was 0.22 °C cooler than the 0.50 °C anomaly measured in November 2009.
Roy Spencer at WUWT just reported the final December 2009 UAH global temperature anomaly. Guess how much:
0.28 °CThat's right: TRF can get a better than 0.01 °C accuracy for the final temperature of a month in the middle of the same month. Read TRF to learn the truth weeks, and sometimes centuries, before others. :-)
This also strengthens the validity of the UAH rankings of 2009.