El Nino is the warming of the Pacific Ocean off of the western coast of South America near Ecuador and Peru. It is called El Nino, or little boy in Spanish, referring to the Christ child because the phenomena was originally noticed near Christmas time. The opposite of El Nino is La Nina, or little girl in Spanish, which is a cooling of the Pacific Ocean. Because the Earth system is interconnected, changes in the ocean cause changes in the atmosphere. El Nino and La Nina events not only impact ocean temperatures in the tropical Pacific, but also global weather. The occurrence of El Nino and La Nina is not predictable, but on average occurs once every four year and usually lasts for about 18 months.
The effects of El Nino and La Nina vary by season. This dataset consists of four frames that show the winter and summer effects of both El Nino and La Nina. The effects of a strong El Nino include a wetter and cooler than normal winter season in the southern United States, though the Pacific Northwest states tend to be warmer. Along the equatorial Pacific, conditions tend to warmer and wetter. Parts of southern Africa tend to be drier and warmer along with southeast Asia. During the summer, El Nino causes southeast Asia to be dry with wetter conditions in the middle of the Pacific. Also, warmer than normal conditions exist along the western coast of South America. A La Nina winter has the opposite impact of an El Nino winter. The results are dry and warm conditions in the southern United States with dry and cool conditions along the equatorial Pacific and a wetter than normal southeast Asia. During the summer, La Nina causes the western coast of South America and southeast Asia to be cooler.
Read more about El Nino and La Nina from the NOAA Climate Prediction Center: