Either way, a VERY respectable anomaly. From a historical standpoint, this could wind up warmer than any December prior to 2015 if PRISM is close. Not sure what's going on with recent Decembers. 3 of the past 4 were even warmer. So from a historical standpoint, EXTREMELY impressive, but from the vantage point of recent years, pretty ho-hum national anomaly. It doesn't appear to be data error, because the USCRN network suggests recent Decembers were even warmer than given by the nClimDiv numbers.