April taken as a single month was the warmest on record for surface temperature, and snow coverage was also unusual, 'April 2007 snow cover extent for the Northern Hemisphere was the third lowest extent on record, and it has been below average in 15 of the past 20 years.' :: NCDC
The National Climatic Data Center have released their summary of global climate findings, as of April. Worryingly, the global average surface temperature was the, 'warmest on record for January-April year-to-date'. Basically, this year has so far been the warmest ever. They go on to say that, 'anomalously warm temperatures have covered much of the globe throughout the year.'