Looks like I was underconfident in retrospect: according to the source that I agreed on when I made the prediction, 2011 was the second-warmest US summer on record.
(Even though it wasn't the warmest on record, the fact that it came in second is evidence that I probably should have estimated this at somewhere around the Intrade global temperature figure of 34%.)
As we did last year, use this thread to make predictions for the next year and next decade, with probabilities attached when practical.
Happy New Year, Less Wrong!