Hottest on record only if you're looking at the surface temperatures that have been adjusted upwards. The satellite record doesn't agree with the adjusted surface temperatures.
See here for the comparison: http://realclimatescience.com/wp-content/uploads/2016/01/2016-01-20-13-31-07.png
The green downward slope is the satellite record, the purple rising slope is the tampered surface record.
Check out how 4 different adjustments to the surface record have turned a downward sloping trend into an upward trend: https://stevengoddard.files.wordpress.com/2013/12/gissustampering1999-20132.gif
Note that this graphic doesn't even contain the tampering in 2014 or 2015 that has suddenly given us a "2015 is hottest ever!!!"
It's pure Fraud.