In the last post I graphed the average temperature for 2015 so far with the annual averages prior to that. It’s certainly not the clearest way to show things, and someone who doesn’t read the text and pay close attention could get the wrong impression. It was also pointed out that there may be seasonal differences in the way temperature has changed; maybe January through April has behaved differently than other times of the year. Finally, the inherent scatter in a 4-month average is bound to be higher than that in an annual average.
In an attempt to present things more clearly, here are a few more views of where we are. We’ll begin with year-long averages for all the data points, but to include the most recent data let’s end each year with April. Here is the average temperature for each May-through-April period since 1880: