In order to determine if 2012 was the hottest year in the US, I need to see the temperatures for the last four days – which are missing. Many stations, Like Lemon Cove, CA have January 2013 data, but no data for December 28-31 2012. Less than 10% of the stations have Dec. 28-31 data listed. That looks very suspicious.
The reason these days are critical is because they were far below normal temperatures. As of November – 2012 was in the number three spot, but a warm first three weeks of December moved it up to #1. If the last four days were more than 10 degrees below normal, then 2012 would drop back to the #2 position.