Pacific sea surface temperatures (Celsius)

According to Australia's weather bureau, ocean surface temperatures in the central equatorial Pacific have continued to warm and now surpass levels typical of an El Nino event by their greatest margin of the year.

 Similarly, the 30-day Southern Oscillation Index has fallen to its lowest value since 2007.

The central equatorial Pacific has warmed significantly through October, while the western Pacific has cooled with the SOI 30-day value down to approximately −12.   A deep and consistently negative SOI pattern (less than about minus 6 over a two month period, with little change over that period)  is a indication of El Nino.

(Note: These negative values are usually accompanied by sustained warming of the central and eastern tropical Pacific Ocean)

The Pacific Ocean sea surface remains significantly warmer than the long-term average over the main El Niño regions.

Trade winds along the equator have eased further, with weakened Trades now extending from the west well into the eastern Pacific.

As a result, tropical ocean temperatures in the central Pacific now exceed their average values by in excess of 1°C. 

Leading climate models suggest tropical ocean temperatures will remain above El Niño thresholds until at least early 2010. 

(El Nino exceed summary)

•  The tropical Pacific Ocean sea surface remains warmer than average and exceeds El Niño thresholds in central to eastern regions. The central Pacific has warmed further and now exceeds average values by the largest amount since late 2006.
• The sub-surface water of the tropical Pacific has warmed further in central regions over the past two weeks, and now exceed 4°C above normal in some regions.
• The SOI has rapidly fallen through October with a 30-day value of approximately −12.
•  Trade winds have continued to weaken across the tropical Pacific in the last two weeks. Weaker than normal Trade flow is now evident across most of the equatorial Pacific.
•  Cloudiness near the date line has generally been greater than the long-term mean over past months. However, when compared with other El Niño events, the current trend in cloudiness is weak.
• Most leading international climate models predict the tropical Pacific sea surface temperatures (SST) to remain above El Niño thresholds until at least early 2010.

Historically, impacts over the United States from El Niño tend to be weak during the summer and strengthen toward the winter months.