Time series plots of the Niño 3 (upper) and Niño 3.4
SST indices as 5-month running means using data from NOAA
and relative to a base period climatology from 1950 to 1979.
Values exceeding thresholds of ±0.5°C for Niño 3 and ±0.4°C for
Niño 3.4 are stippled to indicate ENSO events.