Abstract
The effect of local sea surface temperature changes on frequency shifts in the 40–50 day oscillation is examined using seasonal means. Data were stratified into ENSO (El Niño‐Southern Oscillation) and non‐ENSO years and a significant difference found. In non‐ENSO years, a seasonal shift was noted at some sites. Seasonal frequency means were described qualitatively in terms of sea surface temperatures and changes in zonal circulation cells.