http://cdiac.ornl.gov/ftp/ushcn_daily/state34_OK.txt.gz
The two biggest years for Oklahoma all-time record maximum temperatures were 1936 and 1956. By contrast, 2011 was not much above average.
All years which share a record maximum get counted in the graph above, so there is no bias in either direction.
I believe these last couple summers simply reflect a change from several decades of unusually cool summers back to the kind of summers we had in the 1950’s and 1930’s. Alaska again is well below normal so far in July. It is a weather pattern that we seem to be stuck in, probably related to unusual winter ice and abnormally cold water south and west of Alaska.
Andy DC , isn’t the unusual winter ice and abnormally cold water south and west of Alaska the result of the change in the PDO? If so is’t it likely to continue until it shifts again? Will it be some years before it shifts again ?