Beyond 2016: Year in Review | NOAA Climate.gov
The data aren’t final, but it appears very likely that 2016 will go down as nominally warmer than 2015, which blew away 2014, which was nominally warmer than the rest of the years in modern history.
Why it matters:
Taken individually, especially in a warming world, the “warmest year on record” is not much more than a curiosity item—a headline atop a much broader story. If the world is warming, and it is, a new “warmest year on record” is inevitable every few years. However, one thing makes this year more notable than the other four "warmest years on record" we've had since 2000. 2016 will make a hat trick for 2014-16: three years in a row setting a new record. That’s rare. With the exception of 1939-41, when the NOAA time series was barely in statistical adulthood, this is only time the modern record yields three straight "warmest years on record."