Degree of coloration represents the statistical significance of the relationships. Climate divisions with dots do not have statistically significant relations, but the colors of the dots nonetheless represent the tendency. The following analyses are based on a coarsely gridded monthly precipitation data set prepared by the Climatic Research Unit at the University of East Anglia, United Kingdom. They extend the analysis to Canada and Alaska to the north, and to Mexico to the south.
Coloration again represents the sense of the relationship.
Reddish areas experience wetter winters during El Nino years and drier winters during La Nina years. Bluish areas experience drier winters during El Nino winters and wetter winters during La Nina years. Green areas do not pass statistical significance tests, but tend the same way as bluish areas. Brown areas do not pass statistical significance tests, but tend the same way as reddish areas. Correlation coefficient times 100.