Even before September has ended, 2011 sets the record for the most federally declared disasters ever in any one year. 2011 is already at 84 and will likely add to its notorious place in the record books kept by FEMA. See www.fema.gov/news/disaster_totals_annual.fema.
What year previously had the most disasters? 2010 when 81 federally declared emergencies took place. Back-to-back years for disasters. 2010 and 2011 are also two of the warmest years ever globally and in the USA. Two years does not make a real trend.
But Joe Romm at Climate Progress has a provocative graph of the number of natural disaster going back decades. He also links to science papers drawing a link between rising temperatures and natural disasters. See http://thinkprogress.org/romm/2011/09/26/328856/2011-sets-record-for-most-disasters/