The NCEP/NCAR daily data is in now for December 2014 (here). It was an up and down month - cold start, then very warm leading up to Christmas, then cooling again. The end average was 0.212°C, which makes it a little cooler than August, but a lot warmer than November.
So it is a weakly warming influence on the cumulative sum I am tracking. I'll show below the latest plots of the various indices, in the style of this post and its predecessors; the only update is really HADCRUT. That sum dropped in November, and will be very very close to 2010. NOAA and HADSST3 are well clear, and will be a record. GISS has a fair margin, and should clear.
I'll post in a day or two on the update to TempLS mesh, which should be a better guide to the prospects for GISS.
Update: My TempLS system decides when it can run, based mainly on arrival of ERSST data. It has, and a report is here. Still a lot of land data missing, so I won't post on it for a while. I mention it here because contra NCEP/NCAR, it showed a huge rise in temperature. 0.16°C. That will change, but not greatly, I think. Warmth right across Eurasia, and even N America.
Update: On looking further, this may be an artefact from too little high latitude NH data. ERSST hasn't risen much.
The index will be a record if it ends the year above the axis. Months warmer than the 2010 average make the line head upwards.
Use the buttons to click through.