The month of March was unusually warm in the U.S. Some media have said this is more evidence of, or “consistent with” global warming. See this over-the-top story in the Arizona Daily Star. But the mild winter has nothing to do with anthropogenic global warming.
Even the National Climate Data Center (NCDC) of NOAA does not attribute the warm winter to global warming:
Record and near-record breaking temperatures dominated the eastern two-thirds of the nation and contributed to the warmest March on record for the contiguous United States, a record that dates back to 1895. The average temperature of 51.1 degrees F was 8.6 degrees F above the 20th century average for March and 0.5 degrees F warmer than the previous warmest March in 1910. Of the more than 1,400 months that have passed since the U.S. record began, only one month, January 2006, has seen a larger departure from its average temperature than March 2012.
A persistent weather pattern during the month led to 25 states east of the Rockies having their warmest March on record. An additional 15 states had monthly temperatures ranking among their ten warmest. That same pattern brought cooler-than-average conditions to the West Coast states of Washington, Oregon, and California.
Here is the March temperature record according to NCDC.
Notice that March, 1910, was almost as warm.