Historic El Nino Analyses

With a "possible" El Niño event forecast for next winter it is important to examine the very broad range of past events that make up an "average" El Niño.

Since 1950 there have been a total of 22 El Niños, eight which have been weak, nine in the moderate range and five which have been  categorized as strong. [see Oceanic Niño Index (ONI)].  Even within each of these categories there are huge variations.  See El Niño and La Niña Winter Historic Precipitation & Temperatures, a catalog of events.  

For example, 1977-78 and 1978-79 were weak El Niño events but the winter precipitation patterns and amounts were dramatically different.  The first year, 1976-77, was a drought season in the West (

) while the next year, 1977-78, saw above normal rain in California and much of the West ( ).

The bottom line is that first, any climatology is simply an average over a broad range of previous events.  And second, a climatological analysis is NOT a forecasting tool. 

This and other El Niño data and analyses can be found on the El Niño/La Niña Resource Page.