Wednesday, October 5, 2011

Regional US temperatures, the West, the Middle and the East

The relative changes in the temperature profiles between the Central States and those along the Atlantic Coast, begs the question as to the relative conditions on the West Coast. And so I have combined the state temperatures of California, Oregon and Washington State. As with the other regions the first average that I took was for the homogenized data, and just took an average for the three states, to get a sense of what has occurred over the past hundred and ten years.

Average temperature over time for the Pacific Coast, using the average of state temperatures, and homogenized USHCN reported temperatures

The most obvious immediate conclusion is that the temperature drop from 1950 to 1965 which is so evident on the East Coast does not appear to have happened in the West. And the flat temperatures over the last hundred years found in the Central States don't appear to hold either.

Breaking this down to a review of the initial Time of Observation corrected temperatures, but initially again just averaging the state temperatures, one gets:

Average temperature for the states along the West Coast, averaging the TOBS average state temperatures.

In contrast with the Middle States there does appear to be a steady increase, with time, in the average temperature. Looking at the average of all the stations (a total of 138), the data continues to show that rise:

Average temperature for the states along the West Coast, averaging the TOBS average station temperatures.

The area that each station covers falls from an average of 3,000 sq miles in California, through 2,460 in Oregon to 1,621 in Washington. When one adjusts for area, using this weighting, and adding a trend line to see what the temperature change averages, one gets:

Average temperature for the states along the West Coast, weighting the TOBS averages by area.

There is still no sign of that fall in temperatures in the 1950’s, in fact the temperature goes up. Comparing the results for the three different states:

Average individual West Coast TOBS temperatures over time

The form of the plots are roughly similar with the two more northern states showing almost identical patterns, and a slightly wider range of fluctuation.

When one compares the three regions that I have looked at to date, however, the difference between them is quite clear. Well actually, if I plot the data itself it is a little obscured by the curves as they superimpose.

Average temperatures for different regions of the country over the past century.

The Middle states are clearly warmer than those on the two coasts, which I hadn’t expected, but it is more difficult to separate the two coastal variations. Because of this overlap I have moved the lines a little apart, so that the changes in pattern can be more clearly seen. So, for this plot, ignore the temperature values on the left, since I have, as shown, adjusted the values so that they are separated, and so that the differences in behavior each year can be seen.

Pattern of temperature change for three regions of the United States over the past century.

While there is some congruity between the central and Atlantic values, these are clearly different from the Western states. Perhaps I should see what is happening in the mountains??

I am also curious to see what the effects of El Nino’s have on the land temperatures, but I think that I will add in the mountain states, before putting those effects onto the plot.

I might start here but any other suggestions would be welcome.


  1. Hi there, would you be interested in selling ad space on your blog? Do you have an email address I could reach you at?

  2. Sorry, that would make life more complicated than I would prefer at the moment.