To qualify as a very strong event in our official record, however, we’ll need to see the three-month-average Niño-3.4 index, the Oceanic Niño Index, meet or exceed the threshold. The informal threshold for a “very strong” El Niño event is 2.0 ☌ above average, so we’re there for the second month in a row.
NOAA image based on a graph by Emily Becker and monthly Niño-3.4 index data from CPC using ERSSTv5. 2-year history of sea surface temperatures in the Niño-3.4 region of the tropical Pacific for all events evolving into El Niño since 1950 (gray lines) and the current event (purple line).
