NSW Seasonal Rainfall Outlook: probabilities for November 2004 to January 2005, issued 19th October 2004

Below average falls more likely in eastern NSW

There is a moderate shift in the odds towards below average rainfall for the late spring to mid-summer quarter (Nov-Jan) in the eastern half of NSW, the Bureau of Meteorology announced today. For the rest of the State, the chances of accumulating at least average rain for the coming three months are mostly close to 50%.

probability of exceeding median rainfall - click on the map for a larger version of the map

Through much of the eastern half of NSW the chances of above median rainfall for the November to January period are between 30 and 40%. This means the chances of below median falls are between 60 and 70%. So in years with ocean patterns like the current, about six or seven November to January periods out of ten are expected to be drier than average in eastern NSW, with about three or four out of ten being wetter.

The current pattern of outlook probabilities is mainly due to increasing warmth in the Pacific Ocean.

Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During the November to January quarter, history shows this influence to be moderately consistent across much of NSW (see background information).

Progress towards a late-developing El Niño event has slowed over the past month, with consistent cloud and wind patterns failing to materialize. The central Pacific remains warmer than average and at levels consistent with El Niño, but the Southern Oscillation Index (SOI) was only weakly negative coming in at –3 for September. The approximate SOI for the 30 days ending 16th October was –5.

For routine updates on the latest data relating to El Niño, together with details on what the phenomenon is and how it has affected Australia in the past, see the El Niño Wrap-Up.


Click on the map above for a larger version of the map. Use the reload/refresh button to ensure the latest forecast map is displayed.

More information on this outlook is available from 9.00am to 5.00pm (EST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Sydney Office: (02) 9296 1522.


Corresponding temperature outlook

September 2004 rainfall in historical perspective

July to September 2004 rainfall in historical perspective


Background Information