This seasonal rainfall forecast is a “snapshot summary” of likely rainfall chances and is based on phases or patterns of the Southern Oscillation Index (SOI) (not just its values). Lowest rainfall probability values for this period are in Southern Queensland and Northern NSW.
- The regions shaded red have a 10% to 20% probability of getting or exceeding their long-term median rainfall for this period. That means over the past 100 or so years, following this SOI PHASE pattern, those particular areas have only reached their respective median rainfall in about 10% to 20% of those years.
- Regions shaded beige have a 20% to 30% probability of reaching or getting their long-term median rainfall.
- Regions shaded yellow have a 30% to 40% probability of getting or exceeding their long-term median rainfall and so on.
- Regions shaded light grey have a 40% to 50% probability of reaching or exceeding their median rainfall.
- Regions shaded dark grey have a 50% to 60% probability of exceeding their median rainfall.
- Regions shaded light blue have a 60% to 70% probability of exceeding their median rainfall.
- Regions shaded dark blue have a 70% to 80% probability of exceeding their median rainfall.
- Regions shaded dark blue to black have 80% to 90% or higher probability of exceeding their median rainfall (there are none of these latter regions indicated on this forecast).
Note that this forecast is only for the June to August period. Should the current conditions in the Pacific/Indian Oceans continue, as they currently are forming, then these areas with dark beige or yellow shading (low rainfall forecast regions) will expand over most of eastern Australia – watch this space.
This forecast map is based on interpolation of actual rainfall recording stations in Australia. Of course, each rainfall station would have its unique long-term rainfall records and its long-term median rainfall. The forecast model takes into account all of those rainfall stations and their individual statistics in this compilation.
More detailed interrogation of local rainfall, temperature and streamflow data (where available) is available upon request – and for a fee.
Scientific Reference: Stone, R.C., Hammer, G.L., and Marcussen, T. (1996) ‘Prediction of global rainfall probabilities using phases of the Southern Oscillation Index’ Nature, 384, 252-255, 21 November 1996