http://www.woodfortrees.org/plot/
Wood for Trees maintains copies of all the major climate data from satellite systems and surface records. NASA, Hadcrut, UHI, they are all there. It takes a bit of tinkering to figure out how to use the interface but once you do, you can graph and compare the data any way you like. If you want to compare January temperature trends in the northern hemisphere as recorded by NASA to July temperatures as recorded by Hadcrut (no idea why you would do that, its just an example) for the last 100 years, you can
