http://www.wunderground.com/blog/JeffMasters/show.html
What's truly remarkable is the margin the old record was broken by--spring 2012 temperatures were a full 1°F above the previous most extreme season, the winter of 1999 - 2000. All-time seasonal temperature records are very difficult to break, and are usually broken by only a tenth of a degree. To see the old record crushed by a full degree is a stunning and unparalleled event in U.S. meteorological history.