Are California Coastal Water Temperatures Warmer During El Niño?


Media reports of late, and during past El Niño events, have attributed the presence of warm water species of marine life along the California coast to El Niño. However, a look at the data doesn't support that conjecture. Contextually, the sea surface temperature (SST) warming associated with El Niño occurs in the tropical Pacific, approximately 3,000 miles away from California, plus there is no physical process where that equatorial water is transported to the California coast. And in the short-term, the current El Niño has not even officially formed yet, and most waters along the California coast are below normal.

Historically, during El Niño winters, there are just about equal chances of coastal water temperatures being above or below normal. The following analysis was done by looking at two separate areas along the California coast. In Northern/Central California the study area was a 2-degree square (36° to 38° N and 122° to 124° W) between about Point Reyes and Big Sur and about 100 miles offshore. In Southern California, the area was a 2-degree square (32° to 34° N and 117° to 119° W) between about Santa Barbara and San Diego and about 100 miles offshore,

During the 13 El Niño events since 1980, sorted by strength, the sea surface temperature anomalies (SSTAs) in the northern area were only warmer than normal in 6 of the 13 years.

And along the southern California coast, the El Niño year SSTAs were warmer than normal in 7 of the 13 years.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Twitter: @ggweather