• Based on the Palmer Drought Index, severe to extreme drought affected about 6 percent of the contiguous United States as of the end of January 2011, about the same as last month. About 17 percent of the contiguous U.S. fell in the severely to extremely wet categories.
• About 21 percent of the contiguous U.S. fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of January.

On a broad scale, the 1980s and 1990s were characterized by unusual wetness with short periods of extensive droughts, whereas the 1930s and 1950s were characterized by prolonged periods of extensive droughts with little wetness (moderate to extreme drought graphic, severe to extreme drought graphic).