Seasonal Climate Outlook

Bureau of Meteorology seasonal climate outlook

The Bureau of Meteorology's climate forecast system for monthly and seasonal climate outlooks is the Australian Community Climate Earth-System Simulator – Seasonal (ACCESS–S). It is a dynamical (physics-based) forecast modelling system and is a collaboration between the Bureau of Meteorology and the UK Meteorological Office.

The Bureau of Meteorology’s current seasonal outlook is indicating close to neutral chances 45-60% of exceeding median rainfall for July to September 2020. Predictive skill is poor to good (45-75% consistent). The longer-term outlook for August to October is mostly neutral, with slightly higher chances (60-65%) of a wetter 3-months in the far north. Predictive skill is 50-75% consistent.

Temperature outlooks for July to September 2020, from the Bureau indicate a 65-80% chance of above average day-time maxima (skill 55-75%) and 70-80% chance of above average night-time minima (skill mostly low to very low below 55%) for the SWLD.

Rainfall outlook for July to September 2020 for Western Australia from the Bureau of Meteorology.

Percent Consistent skill of the Bureau of Meteorology’s outlook for July to September.

Looking at other models, the majority are indicating above chances of exceeding median rainfall for July to September.

Model distribution summary of 13 models which forecast July to September, rainfall in the South West Land Division.

SSF Forecast for July to October

For July to October, the SSF is close to neutral (40-60%), with higher chances of exceeding median rainfall for parts of the north, east and southern grainbelt. The most probable rainfall decile map indicates decile 8-9 for the majority of the SWLD, with decile 4-7 elsewhere. Predictive skill based on June conditions is poor to moderate (50-70% consistent).

SSF forecast of the probability of exceeding median rainfall for July to October 2020 using data up to and including June.

Percent Consistent skill of the SSF at forecasting July to October rainfall using data up to and including June.