See a National Journal article for an impressively complex discussion of what pushes climate temperatures in one direction or another. Solar cycles, volcanic activity, human actions, deforestation, and increasing access to autos in the third world - all of these may play parts in the never-completely-understood climate model.
All we know for certain is that climate will change, has done so for millennia. That's the story on the global level, on a more local, personal level, see below.
For years, my standard trope for describing the climate in our part of northern CA has been that we have 30 days over 100 F and 30 days below 32 F (freezing). However, the place where the DrsC have their winter home has been dramatically less hot this summer, plenty of days in the 90s but not so many 100s. I may have to change my standard description if summers continue to be cool.
