Seasonal Climate Outlook Message for December 2009 to March 2010

The bottom line

SOI in Consistently Negative Phase Dave McRae, Qld Climate Change Centre of Excellence, 01/12/09.

The monthly SOI value for October was minus 14.8 and for November was minus 6.4. Based on these values the SOI is in a Consistently Negative SOI phase at the end of November.

An analysis of historical rainfall records and a Consistently Negative SOI phase indicate that there is a relatively low 20 to 40% chance of getting above median rainfall for December to February throughout most of Queensland. The exception is for the far western border regions of Queensland where there is a marginally higher 40 to 50% chance of getting above median rainfall for December to February.

It is worth noting that even for those areas with a relatively low chance of getting above median summer rainfall, that as we are entering our rainfall season there is still a reasonable chance of getting some useful relief rain.

For those who like to follow the relationship between the SOI and rainfall patterns in more detail have a look at what happened in your area during December to February in the following years since 1900 that have had a 'Consistently Negative' SOI phase at the end of November; 1901, 1911, 1913, 1914, 1919, 1925, 1939, 1940, 1941, 1944, 1951, 1963, 1965, 1972, 1977, 1982, 1991, 1992, 1994 and 1997.

It can be useful to find out what rainfall and farming conditions where like in your area for December to February in those years. For more information try or Rainman StreamFlow.

When using a climate forecast you should remember that the probability or percent chance of something occurring is just that - a probability. For example if there is a 70% chance of recording more than 100 mm there is also a 30% chance of recording less than 100 mm i.e. 70-30; 30-70. It does not mean that you will get 70% more than 100 mm or 100 mm plus another 70%.

The Bureau of Meteorology has just issued a seasonal temperature outlook for summer. Currently there is a 60 to 70% chance of getting above long term median maximum temperatures for December to February throughout most of Queensland.

The increased likelihood of above average temperatures across northern Australia during summer is mostly due to the El Niño pattern currently persisting in the Pacific Ocean. (

You can receive a text message with the latest SOI values sent to your mobile phone. To subscribe to this free service, e-mail The latest rainfall probability maps are also available at

Last updated: 30 November 2009