Just this past winter my area had the coldest weather it's ever had in 97 years, and record snow and ice in several areas. Global warming my ass.
But this is tornado alley, so I guess tornadoes are typically our biggest problem. Lots of people in St. Louis got hit bad by one a few days ago (the airport was shut down for a few days, too), and in January one of my relatives and many others in my hometown lost their houses to a tornado.
But, I also live near the New Madrid Fault, which is the source of the largest earthquake in recorded US history (so powerful it made parts of the Mississippi River flow backwards), so if you really want to get technical it's probably that.