Confirming what many of us have already noted from the anecdotal evidence coming in of a much cooler than normal May, such as late spring snows as far south as Arizona, extended skiing in Colorado, and delays in snow cover melting, (here and here), the University of Alabama, Huntsville (UAH) published their satellite derived Advanced Microwave Sounder Unit data set of the Lower Troposphere for May 2008.
It is significantly colder globally, colder even than the significant drop to -0.046°C seen in January 2008.
Read the whole thing here.