Forecasts

May shows strong rainfall signals, June continues this trend, and while July appears more average, further events are expected. August favours the southwest and southeast, while spring shows near to above average rainfall, with increasing storm activity inland. Despite El Niño and IOD discussions, the current pattern suggests a strong northwest cloud band season, with consistent moisture transport from the Indian Ocean.

Late-April Rainfall Signal Strengthens as Northern Moisture Links with Southern Systems

Attention then turns very quickly to the next key feature in the pattern, and this is where the forecast becomes far more significant. From around the 9th to the 12th of April, there is increasing model agreement on the development of a tropical low in the Timor Sea or Arafura Sea region. Sea surface temperatures remain elevated, sitting around 29 degrees, which is more than sufficient to support cyclone development. While we are still some time out, the consistency in the s

Video Summary: Today’s video update discusses the building national weather phase currently developing across Australia, bringing a renewed round of storm activity through southern Western Australia, South Australia, Victoria and New South Wales. This emerging phase is also helping to re-establish long-range atmospheric pathways linking northern Australia with the south and south-east. These corridors are a critical component of both historical rainfall patterns and upcoming

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For April 2026, most climate guidance and pattern analysis suggests the month will lean drier overall, with meaningful rainfall concentrated into a small number of defined weather windows rather than widespread activity.

The pattern ahead sets the stage for the next High Energy Period, focused primarily over the western basin from 8–12 December. Current model guidance indicates Cyclone Genesis near 112–114° E, with the system expected to drift south toward the Pilbara coast by mid-month. Secondary tropical lows are likely to form across the Arafura Sea and near 160° E between Vanuatu and New Caledonia, each forecast to track southeastward.

December marks the transition into early summer, with increasing solar input, warmer surrounding seas and the build-up of the northern wet season. From August through November, rainfall decile patterns have maintained a strong contrast of a drier trend across the south-east and eastern interior, and a wetter to average signal across the north-west and western regions. By averaging the four-month decile trend, December shows a clear continuation of this divide: drier in the s

October 2025 has continued the prevailing theme of below-average rainfall, persistent heat, and inconsistent model performance across much of Australia. Despite sporadic thunderstorm activity and the emergence of a cloud band through the northwest interior late in the month, broad-scale relief has remained elusive. Temperatures have been markedly above average, reinforcing the dominance of high-pressure blocking and limited atmospheric coupling throughout spring.

While mainstream guidance expected a widespread wet spring, OIF’s caution of a drier-leaning start to spring has proven accurate, highlighting the value of including non-traditional drivers beyond ocean indices in seasonal risk assessments.

September long-range review: With a Negative IOD in the background, spring leans drier overall, with coast-favoured rainfall and one major risk window mid-month. We outline climate drivers, temperature signals, and the exact dates most likely to deliver weather of impact, so you can plan works and operations with lead time. Read the full members-only breakdown and weekly refinements through March 2026.

Timing Expectations Primary Window: 18–24 July ↳ NW CBs are climatologically favoured in this period, especially under a -IOD influence Secondary Window: 3–10 July ↳ Should this period not yield widespread NW CB development, attention shifts strongly toward the mid-late month window