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El Niño and La Niña are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific. As we begin the latest La Niña phase, we can take a little time to learn about their history and what they really mean for our current weather and climate.


El Niño means the Little Boy – or Christ’s Child – in the Spanish language. It was originally recognised by fishermen off the coast of South America in the 1600s, and was formed by the appearance of unusually warm water in the Pacific Ocean for a certain time of the year. The name was chosen based on this time of year (which was around December), during which these warm water events tended to occur more often.

In modern times, the term El Niño refers to the large-scale ocean-atmosphere climate interaction that is linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific region. Typical El Niño effects usually develop over the Northern America continent during the winter season, and is signified by warmer-than-average temperatures over western and central Canada, as well as over the western and northern United States. Wetter-than-average conditions are likely over portions of the U.S. Gulf Coast and Florida, while drier-than-average conditions are found in the Ohio Valley and the Pacific Northwest. The presence of El Niño can significantly influence weather patterns, ocean conditions, and marine fisheries across large portions of the earth for an extended period of time, and have significant causal effects on other weather-related events.



La Niña, on the other hand, is Spanish for the Little Girl. La Niña is also sometimes known locally as El Viejo, anti-El Niño, or ‘a cold event’. Simply put, it forms the opposite conditions to the El Niño event.

La Niña episodes represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific. La Niña impacts on the global climate tend to be opposite those caused by El Niño, and in the tropics, ocean temperature variations in La Niña also tend to be on the opposite end to the weather patterns attributed to El Niño. In general, during a La Niña year, winter temperatures are warmer than usual in the southeast of the Northern American continent, and cooler than normal in the northwest.


Source: https://oceanservice.noaa.gov/facts/ninonina.html