Indonesia's coal export supply chain is facing increasing weather-related risks as below-normal rainfall in parts of Kalimantan and Sumatra raises concerns over falling river levels that could slow barge movements from inland mines to export terminals during the peak dry season.

Sources told Sxcoal that some coal-producing areas in Indonesia have recently recorded lower rainfall compared with the same period last year, prompting miners and traders to closely monitor river conditions. Although no significant disruption to coal exports has been reported so far, prolonged dry weather could gradually affect logistics efficiency if water levels continue to decline.

Indonesia's Meteorology, Climatology, and Geophysical Agency (BMKG) forecasts a drier-than-normal dry season in many parts of the country in 2026. BMKG said more than half of Indonesia's seasonal rainfall zones are expected to experience below-normal rainfall, with the most widespread dry conditions likely occurring around August.

During a press briefing in Jakarta on July 30, BMKG predicted the El Nino phenomenon will persist at least until the beginning of the first quarter of 2027, with peak intensity exceeding the strong category.

This situation is further compounded by a forecast positive Indian Ocean Dipole between September and December 2026, a combination that typically suppresses rainfall across much of the Indonesian archipelago.

Indonesia's coal industry remains highly dependent on river transportation, particularly in Kalimantan and Sumatra, where many mines are located inland and rely on barges to move coal to coastal loading facilities. Unlike major exporters such as Australia that primarily use rail networks, Indonesia's coal logistics system is intrinsically tied to waterway conditions.

In East Kalimantan, producers around the Mahakam River rely on waterways to transport coal from mine areas to transshipment facilities. Similar logistics systems operate along the Barito River in South Kalimantan and the Musi River in South Sumatra.

When river levels fall, mining companies typically reduce barge loading capacity to avoid vessels running aground. The result is usually higher transportation costs, fewer tonnes moved per trip, longer loading schedules and potential delays in coal deliveries to offshore transfer points. This could tighten prompt cargo availability even if total annual production remains unaffected.

The impact is usually more significant for smaller miners and inland operations that have fewer alternatives, while larger producers with better infrastructure and access to multiple logistics routes are generally more resilient.

Historical experience showed that drought typically affects coal exports through transportation bottlenecks.

During the strong El Nino event in 2015, prolonged dry conditions lowered water levels in several regions and disrupted river transportation efficiency in parts of Kalimantan and Sumatra. Similar issues emerged during the 2019 dry season, when some coal operators faced difficulties moving cargo due to reduced barge capacity. However, the impact remained concentrated in specific mining areas and did not lead to a significant decline in Indonesia's total annual exports.

Market participants said the immediate impact remains limited, but continued monitoring of river levels in major coal-producing regions will be critical. The key period to watch this year will be August to October, which is traditionally one of Indonesia's stronger export windows. Coal shipments often increase during this period as Asian buyers prepare for higher year-end and winter heating season demand and build inventories before the return of heavier rainfall later in the year.

For now, the market focus remains on rainfall trends and river conditions across major coal-producing regions. A weather-driven supply disruption could provide some support to Indonesian coal prices by tightening spot availability. However, it is unlikely to trigger a major price rally unless drought conditions become severe enough to significantly reduce export volumes.

This is because Indonesia's coal export outlook also faces additional uncertainty from policy changes and demand conditions beyond weather risks. The government plans to push forward for its planned single-gate export through state-run PT Danantara Sumberdaya Indonesia (DSI) from January 1 next year to September 1 this year, although many market participants remain skeptical about whether a full transition can be implemented smoothly within the revised timeframe.

Meanwhile, uncertainty remains over potential additional production quotas for the 2026 RKAB. Participants widely believe that the overall addition will not be significant, and a large share of it will be required for domestic obligations, leaving the actual increase in supply to the export market limited.

On the demand side, weaker coal purchasing appetite from China and India, Indonesia's two largest export markets, could offset some supply-side pressure. High coal inventories and expanded renewable power generation, as well as still sufficient domestic supplies, made buyers more cautious.