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High Energy Period Triggers Cyclone Risk in the Northwest as Heatwaves Dominate the Interior and Storm Bands Build Across Eastern Australia

Following on from the major cycle that was forecast to conclude around the 11th, an interesting and important observation is now emerging. Once Tropical Cyclone Koji crossed the coast on the 11th, the period of widespread high-impact rainfall effectively ended. Since that point, even though Ex-Koji has continued to track across the interior, rainfall has been far more fragmented and localised, occurring mainly in pockets of convection near the remnant circulation rather than

Tropical Low 12U continues to develop in the western Coral Sea and is tracking toward the northeast Queensland coast. While model guidance indicates a moderate risk of cyclone development late Friday into Saturday, the primary and most immediate threat is extreme rainfall, not wind intensity.

Australia is entering a high-impact weather period, with multiple hazards unfolding simultaneously across different regions. The national pattern remains sharply divided, with a developing tropical system bringing increasing flood and wind risk to the northeast, while extreme heat, dryness and escalating fire danger continue across the south and southeast. The lack of overlap between these regimes is critical, as there is no rainfall relief forecast for fire-prone southern re

Australia remains in an exceptionally high-energy pattern, with multiple hazards occurring simultaneously. The key theme through to the 11th is the continued dominance of the monsoon in the north and northeast, while dangerous heat and fire weather escalate across southern and western regions.

Satellite imagery 31.12.2025

A prolonged weather event is expected to persist into 7–11 January 2026, continuing the active monsoonal pattern that has dominated since late December. A key contributing factor lies in a series of Earth-facing coronal holes that developed during week four of December 2025, a phenomenon that was highlighted in previous Oz Industries Forecasting updates.

The High Energy Period (HEP) from 18 to 24 December is now moving through its peak phase. The 21 to 24 December window has proven to be the wetter segment of this period, with a marked increase in thunderstorm activity across the southeast over recent days. Areas of southeast South Australia, Victoria, New South Wales and parts of southern Queensland have experienced a surge in storms, with recorded rainfall totals generally ranging from 5 to 50 mm, and isolated pockets of 5

As the monsoon strengthens, high-impact rainfall is forecast to build across the northeast from late December, continuing into early January 2026, with the most intense period likely between 31 December and 11 January.

In today’s update, we unpack the next major weather cycle set to unfold from late December leading into the first tropical phase of the 2025–2026 season across northern Australia. Expect a noticeable build-up of heat, moisture, and storm energy through the north and northeast, with high-impact rainfall likely developing into week two of January 2026.

Monday 15 December to Sunday 22 December This week is shaping up as a classic pre Christmas contrast across Australia.Heat dominates the north and interior, while the south experiences very strong winds, rough seas and sharp temperature swings. As we move toward 18 to 24 December, the atmosphere becomes more energetic, increasing the risk of severe thunderstorms and localised heavy rain, especially inland and across parts of the east.

Today’s update covers the developing weather signals across Australia as we transition from the current dry and heating phase into the next High Energy Period and tropical cyclone genesis window due 8 to 12 December.

The current High Energy Period (19–24 November) reaches its peak today, coinciding precisely with the maximum intensity of Severe Tropical Cyclone Fina. The system is now beginning to weaken and will continue tracking southwest towards the North Kimberley coast and Mitchell Plateau from 25 November onwards.

A highly dynamic national pattern is unfolding, driven by Tropical Cyclone Fina across the northern Top End, widespread severe heat across inland Australia, and increasing thunderstorm activity along the eastern seaboard.

Tropical Cyclone Fina Update – Alignment with the 19–24 November High-Energy Period

High Energy Period 19-24th Intensifies: Tropical Low 02U and the Escalation of National Severe Weather