SOI (SOUTHERN OSCILLATION INDEX)

The middle of June saw a sharp rise in the 30-day SOI, returning to near zero. It has generally remained near zero since. The official monthly SOI for September was +0.4. For July and August, the monthly values of the SOI were 0.0 and -0.8 respectively. The 5-month running mean centered on July was approximately - 0.3. With the climate expected to continue in a state of ENSO Neutral, the SOI should average near zero for the next three to six months, with month to month fluctuations within the range of -1.0 to +1.0.