March of 2012 was the warmest on record, according to data from NOAA. Scientists at the National Climatic Data Center animated the locations of each of the "7,755 daytime and 7,517 nighttime records (or tied records) in sequence over the 31 days in March."
For more data, see the State of the Climate blog, where NOAA explains how drastic these records are:
The average temperature of 51.1°F was 8.6 degrees above the 20th century average for March and 0.5°F warmer than the previous warmest March in 1910. Of the more than 1,400 months (117+ years) that have passed since the U.S. climate record began, only one month, January 2006, has seen a larger departure from its average temperature than March 2012.
For more videos from NOAA, visit the YouTube channel.
Thanks to Ian Muir for the video.