The two extreme phases of the global ENSO phenomenon, El Nino and La Nina, have strong signals in seasonal U.S. weather. Shifts occur in both the expected temperature and precipitation patterns, as well as the frequency of extreme seasons (e.g. severe droughts, heat waves). Using the NCDC climate region dataset, both the average and extremum changes associated with El Nino and La Nina periods are determined and examined for statistical significance. Most regions exhibit statistically significant anomalies with one or more seasons, and many regions are found to have reliable shifts in the probability of extreme seasons. These changes are shown to have implications for measures of fire danger.