Ex-Tropical Cyclone Koji formed on 10 January 2026 and made landfall between Ayr and Bowen on 11 January as a category 1 system. The system moved through the Central region of the Marine Park between Ayr and Mackay, bringing heavy rainfall. Early reports indicate flood plumes have formed in the Marine Park from nearby catchments, and flood warnings remain in place. Freshwater runoff into the Marine Park is expected to continue, and river plumes are being surveyed by the Marine Monitoring Program.

Temperature

From 5 to 11 January 2026, sea surface temperatures dropped slightly by 0.2−0.3°C across the Marine Park but remain approximately 0.4−0.9°C above average in all regions.

In the Northern, Central and Southern regions of the Marine Park, temperatures are not high enough to build up heat stress.

In the Far Northern region, heat stress is still building with most reefs under a Bleaching Warning or Watch level, meaning coral bleaching is possible. A few reefs near the Torres Strait boundary are under Bleaching Alert Level 1, meaning there’s a risk of some reef-wide bleaching if warm conditions continue.

Rainfall

During the reporting period, rainfall exceeded 200mm in many parts of the Cape York, Wet Tropics and Burdekin catchments, with some rainfall stations recording over 300mm in the Mackay−-Whitsundays region.

Reef health

During the survey period, 33 Reef Health Impact Surveys were carried out on three reefs in the Far Northern and Northern regions, and no coral bleaching was observed. However, bleaching was reported eight times through 23 surveys from other Eye on the Reef monitoring programs, across the Northern, Central and Southern regions.

Due to the high rainfall in the catchments adjacent to the Marine Park, early satellite imagery and reports from the ongoing water quality monitoring conducted by the Marine Monitoring Program indicate flood plumes have developed in the Marine Park across the affected catchments.

Crown-of-thorns starfish control

As of 31 December 2025, crown-of-thorns starfish (COTS) outbreaks are impacting reefs throughout the Marine Park, with the most severe outbreaks occurring in the Southern region (Swain Reefs) and in the Northern region between Cairns and Lizard Island. The COTS Control Program and Reef Joint Field Management Program (RJFMP) COTS response teams have actioned 128 reefs for surveillance and culling where required.

- COTS are at sustainable levels for coral growth and recovery at 44 actioned reefs

- Cull operations are currently active at 63 reefs to suppress outbreaks and protect coral from starfish predation.

- COTS have been detected on 21 reefs and culling will be initiated when resources are available.

Following recent rainfall across parts of northern Queensland, the Reef Authority is working closely with our partners to monitor conditions across the Marine Park.

The Bureau of Meteorology forecasts a monsoon trough will develop in the coming days, along with a tropical low off the coast of far northern Queensland. This is expected to bring high levels of rainfall to catchments of the Wet Tropics and Cape York with a moderate chance of it developing into a tropical cyclone by 8 January 2026.

Temperature

From 29 December 2025 to 4 January 2026, sea surface temperatures across the Marine Park remained above average, with the highest temperatures recorded in the Far Northern and Northern regions at 29.1−29.8°C. Waters were slightly cooler in the Central and Southern regions at 28.6−28.3°C.

Most reefs in the Far Northern region are under Bleaching Warning conditions and are continuing to accumulate heat stress. Some reefs close to the Torres Strait boundary in the Far Northern region have reached Bleaching Alert Level 1, meaning some bleaching is expected if warm conditions continue.

Rainfall

The onset of the Australian summer monsoon brought heavy rainfall across Great Barrier Reef catchments, with the Normanby and Burdekin catchments receiving over 200mm, and some parts of the Wet Tropics receiving over 1000mm.

Reef health

Over the survey period, a total of 11 Reef Health Impact Surveys (RHIS) were conducted on four reefs across the Marine Park. High (31–60%) coral bleaching prevalence was recorded at one reef in the Northern region, and the presence of coral bleaching was reported on seven other occasions from 18 surveys conducted by other Eye on the Reef monitoring programs. Due to the high rainfall in the catchments adjacent to the Marine Park, there will be runoff flowing into the Marine Park, along with the potential for flood plumes. Inshore coral reefs and seagrass meadows may be exposed to reduced salinity and sedimentation. The Marine Monitoring Program has been in the field sampling water quality from the Tully River flood plume arising from minor flooding between Cairns and Townsville.

Crown-of-thorns starfish control

As of 31 December 2025, crown-of-thorn starfish (COTS) outbreaks are impacting reefs throughout the Marine Park, with the most severe outbreaks occurring in the Southern region (Swain Reefs), and in the Northern region between Cairns and Lizard Island.

The COTS Control Program and Reef Joint Field Management Program COTS response teams have actioned 128 reefs for surveillance and culling where required.

• COTS are at sustainable levels for coral growth and recovery at 44 actioned reefs.
• Cull operations are currently active at 63 reefs to suppress outbreaks and protect coral from starfish predation.
• COTS have been detected on 21 reefs and culling will be initiated when resources are available.