Post-Irene, the Heritage Foundation flags a report it recently released:
In the course of 16 years, the yearly average of Federal Emergency Management Agency (FEMA) declarations tripled from 43 under President George H. W. Bush to 89 under President Bill Clinton to 130 under President George W. Bush. In his two and a half years in office, President Obama has issued 360 declarations without the occurrence of one hurricane or large-scale earthquake. In the first six months of 2011, President Obama issued 144 declarations, which puts him on pace for 288 declarations for the year—by far the most in FEMA history. The current single-year record is President Clinton's 157 declarations in 1996.
For those interested in the topic, the August 24, 2007 New York Sun editorial Disaster Inflation is also well worth a look:
It's not that storms, fires, and floods are twice as common now as they were in the 1950s and 1960s, but that state and local politicians are twice as quick to cry to Washington for help, and Washington is twice as ready to open the federal funding spigot in return. Disasters of federal magnitude seem more common in presidential or congressional election years. Again, we doubt that storms, fires, and floods are more common in election years; it's just that in an election year, the White House is less likely to decline a state request for assistance, and more likely to be generous with taxpayer funds.