Oceania's H1 2026 alumina production falls 3.2% as refinery capacity and weather disruptions weigh

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Oceania produced 8.194 million tonnes of alumina in H1 2026, down 3.23 per cent from 8.467 million tonnes in H1 2025. The region’s average daily production also declined to 45.27 thousand tonnes, from 46.78 thousand tonnes a year earlier, a decrease of 3.23 per cent.

On a quarter-on-quarter basis, production declined from 4.142 million tonnes in Q1 2026 to 4.052 million tonnes in Q2, a decrease of 90,000 tonnes, or 2.17 per cent. The daily average fell from 46 to 44.5 thousand tonnes, down 3.26 per cent.

Compared with Q1 2025, production in Q1 2026 was 4.142 million tonnes, down 170,000 tonnes, or 3.94 per cent, from 4.312 million tonnes. The daily average also fell from 47.9 to 46 thousand tonnes, a decline of 3.97 per cent.

In Q2, production stood at 4.052 million tonnes, compared with 4.155 million tonnes in Q2 2025. This represents a year-on-year decline of 103,000 tonnes, or 2.48 per cent, while the daily average decreased from 45.7 to 44.5 thousand tonnes, down 2.63 per cent.

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Why did Oceania's alumina production decline?

One of the biggest structural factors was the loss of Alcoa’s Kwinana alumina refinery in Western Australia. Alcoa permanently closed the refinery after previously curtailing production in 2024. The facility had an annual capacity of 2.2 million tonnes. 

Alcoa said the closure reflected several factors, including the refinery’s age, scale, operating costs, market conditions and bauxite grades. With Kwinana no longer producing alumina, Oceania entered 2026 with less refining capacity than it had previously.

The first half of the year also brought temporary operational disruptions. Cyclone Narelle affected operations in Australia, with Alcoa reporting that instability at its Pinjarra refinery, which began in late March, was further exacerbated by gas supply disruptions associated with the cyclone. 

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The company subsequently lowered its 2026 alumina production forecast, citing lower production at Pinjarra. Heavy rainfall at Rio Tinto’s Weipa bauxite operations in January and February, followed by Tropical Cyclone Narelle in March, also disrupted bauxite mining and logistics.

Earlier in the year, Alcoa reported that Q1 alumina production was affected by seasonal maintenance at its Australian refineries, while weather and logistics disruptions contributed to delays in Australian alumina shipments.

Beyond these operational disruptions, weaker alumina prices added further pressure on regional refining economics. The Platts alumina index traded at roughly USD 303-330 per tonne in Q2 2026, while the ex-China seaborne market remained oversupplied, squeezing refiner margins. 

Alcoa’s figures reinforce this trend: its average realised third-party alumina price fell to USD 324-334 per tonne in H1 2026, from USD 475 per tonne a year earlier, while its adjusted operating cost per tonne shipped rose to USD 352 from USD 318. The combination of lower realised prices and higher costs created a significant margin squeeze, increasing the incentive to trim production.

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