This page is based on work-in-progress by Klaus Wolter, Jon Eischeid, Randy Dole, Robin Webb, and Cathy Smith of the NOAA/ESRL Physical Science Division. It replaces an earlier version that used data from 1896-1995 and was described in Wolter et al. (1999). We acknowledge the Physical Science Division in the publication. Information and image provided by the NOAA/ESRL Physical Science Division, Boulder, Colorado, from their web site at: http://www.esrl.noaa.gov/psd/enso/climaterisks.