The researchers say their climate simulations indicate extreme weather events may be caused by interaction between greenhouse gas concentrations and local geographical features.
Noah Diffenbaugh and colleagues note the United States experienced many more such events during the latter part of the 20th century.
The scientists combined historical weather data with mathematical models of global, regional, and local climate systems. They say the results suggest trends from the last century will continue during this century if atmospheric greenhouse gases continue to rise at their current rate.
"One of the difficulties in preparing for climate change is getting the spatial nuances," said Diffenbaugh. "Now we have projections for the whole lower 48 (U.S. states) with the kind of spatial detail that matters for a power supplier, or a water utility, or a wine maker.
"And we're seeing that the spatial detail really matters for getting climate change projections correct, especially for extreme events."
The research is detailed in the online early edition of the Proceedings of the National Academy of Sciences.