Jakarta. The Meteorology, Climatology and Geophysics Agency (BMKG) has warned that Indonesia's 2026 dry season will be drier and longer than usual due to a strong El Niño event and a positive Indian Ocean Dipole (IOD).

The Katulampa Weir in East Bogor, West Java, has dried up after more than 20 days without rain, exposing the riverbed and underscoring the severity of the drought. The weir, which serves as Jakarta's primary flood early warning station by monitoring water levels in the Ciliwung River, is typically associated with flood risks during the rainy season.

Although rain has fallen in parts of Bogor over the past two days, the Katulampa area, along with much of West Java, has remained unusually dry throughout July due to below-average rainfall.

Supari, BMKG's coordinator for climate variability analysis, said historical data show that strong El Niño events significantly reduce rainfall across Indonesia, increasing the risk of widespread drought.

"This year, the country is also expected to experience a positive Indian Ocean Dipole (IOD), a climate phenomenon in the Indian Ocean that can further suppress rainfall over Indonesia," he told Beritasatu TV.

The last major positive IOD occurred in 2019, when Indonesia experienced one of its most severe droughts in recent years.

According to BMKG, the positive IOD is forecast to develop in August. It occurs when sea surface temperatures near eastern Africa become warmer than average while waters near Indonesia cool. This pattern suppresses cloud formation over Indonesia, resulting in lower rainfall, drier conditions, and a higher risk of drought.

Although the positive IOD typically lasts less than a year and is unlikely to prolong the dry season, it is expected to intensify dry conditions by further reducing rainfall when combined with El Niño.

"According to BMKG's forecast maps, the regions expected to experience the most severe drought are southern Sumatra, Java, Bali, West Nusa Tenggara, East Nusa Tenggara, southern Kalimantan, most of Sulawesi, Maluku, North Maluku, and western and southern Papua," Supari said.

"These regions are expected to receive very low rainfall, particularly in August and September," he added.

The drought has already begun affecting agriculture. As of July 10, around 30,379 hectares (75,070 acres) of rice fields nationwide had been hit by drought, with 12,207 hectares suffering complete crop failure, according to the Agriculture Ministry. Most of the damaged area is in South Sulawesi, although several other provinces have also reported losses.

Despite forecasts that this year's dry season will coincide with El Niño conditions, the government expects crop losses to remain manageable through a combination of prevention, adaptation and mitigation measures. These include distributing more than 57,000 water pumps, rehabilitating irrigation networks with a 16.4 trillion rupiah ($912 million) budget this year, promoting drought-resistant rice varieties, expanding agricultural insurance and strengthening early warning systems.

The National Food Agency has also sought to reassure the public that national food supplies remain secure despite weather-related risks.

Supari said the most immediate consequence of a prolonged dry season would be dwindling supplies of clean water as rivers, reservoirs, and other natural water sources dry up.

"We strongly encourage the public to conserve water and use it efficiently. The first sector to be affected is the availability of clean water, particularly from natural water sources," he said.

He also urged farmers to adjust planting strategies by choosing more drought-resistant crops and preparing alternative irrigation sources as river flows decline.

Supari said weather modification operations, or cloud seeding, could help increase rainfall but would only be effective if sufficient rain-bearing clouds were present.

"Weather modification cannot create rain from clear skies. It can only enhance the potential for rainfall from existing clouds," he said.

He added that the current prevalence of clear skies and limited cloud formation has reduced the effectiveness of cloud-seeding operations. However, if BMKG detects adequate cloud development, the government could consider deploying weather modification as one option to help mitigate the drought.