In preparation for an upcoming talk, I have updated the figure above to the start of the 2012 hurricane season, which will begin with a record-long stretch of no intense hurricane landfalls still continuing. (In most browsers you can click on the figure for a larger view.) The long stretch with no intense hurricane landfalls has surely shaped expectations, setting the stage for all sorts of animal spirits to be in play. Oh, to be a commodities trader this summer.
Below is a figure showing the intra-seasonal distribution of US intense hurricane landfalls. About 8% have occurred in June and July, and more than 75% in August in September. (UPDATE: This figure has been updated from the original posted to fix an error in the median date.)