Not to Make Rain, BMKG Explains Reasons for Weather Modification in IKN
Jakarta, CNBC Indonesia - Weather Modification Operations (OMC) are often used by the government to suppress and prevent the increased potential for hydrometeorological disasters, such as those currently occurring, where drought and forest and land fires (karhutla) are affecting regions across Indonesia.
In this case, the Meteorology, Climatology and Geophysics Agency (BMKG) together with the Nusantara Capital City Authority (OIKN), the Indonesian National Armed Forces - Air Force (TNI-AU), the National Disaster Management Agency (BNPB) and the East Kalimantan Provincial Government are carrying out weather modification operations as an effort to address the water deficit in Sepaku Reservoir and forest and land fires.
However, BMKG Director of Weather Modification Operations Budi Harsoyo stated that the weather modification operation is not being carried out to make rain.
So why is it still being conducted?
BMKG cited data from the IKN Authority showing that water reserves in Sepaku Reservoir, which serves as the raw water source for the IKN area, have continued to decline since July due to the impact of El Niño.
Meanwhile, based on BMKG monitoring, the number of hotspots in East Kalimantan from 1-23 August 2026 reached 13,273 points. This figure increased by 35.5% compared to the same period in 2015, precisely when the peak of the dry season coincided with El Niño.
Data as of 20 August 2026 shows that East Kalimantan generally experienced Very Short to Long category Days Without Rain (HTH), with the longest duration recorded in West Kutai Regency and Paser Regency at 28 consecutive days without rain.
At the same time, smoke from forest and land fires in Kalimantan has begun to cross national borders. According to BMKG, the smoke generally moves northwest to northeast, crossing administrative boundaries into North Kalimantan and Sabah, Malaysia.
“Weather modification is not about making rain, but optimising the available cloud potential. If cloud conditions are supportive, cloud seeding is carried out to accelerate the process of rainfall and expand its area,” said Budi, quoted from the official BMKG website, Wednesday (26/8/2026).
Based on BMKG monitoring, there is potential for cloud growth in East Kalimantan. From 23-31 August, the potential is high to moderate, especially in the northern part of East Kalimantan. However, there is a decline in cloud growth potential from 28-31 August, resulting in relatively dry weather across most of East Kalimantan.
There is potential for light to moderate intensity rain in western, northwestern and northern East Kalimantan on 24-26 August. From 27 August to 1 September, the potential intensity and distribution of rain is expected to decrease significantly across most of East Kalimantan.
“In implementing the OMC, BMKG does not only consider the number of detected fire spots, but also the rain potential in the target area,” said Budi.
Severe Effects of Very Strong El Niño and Positive IOD
Indonesia is currently experiencing the dry season. At the same time, the El Niño climate phenomenon and a positive Indian Ocean Dipole (IOD) index are occurring. The IOD indicates the sea surface temperature phenomenon in the Indian Ocean.
BMKG, in its Atmospheric Dynamics Analysis for the Second Dasarian of August 2026 released on 24 August 2026, confirmed that a very strong El Niño is ongoing. The combination with a positive IOD, according to BMKG, is worsening the intensity of the dry season in Indonesia, making it drier and hotter.
BMKG has issued a Meteorological Drought Early Warning effective for the Third Dasarian of August 2026.
The Alert category (Waspada) applies to central and northern Kalimantan, small parts of Sulawesi and Maluku, and southern Papua.
The Standby category (Siaga) applies to several areas in southern Sumatra, western and central Java, most of Kalimantan, parts of northern and southern Sulawesi, most of the Maluku islands, and southern Papua.
The Warning category (Awas) applies to most of Java and Nusa Tenggara, as well as small parts of South Kalimantan and Maluku.
BMKG forecasts that dasarian rainfall in the period August III-September II 2026 will be in the Low-Medium category (0-150 mm/dasarian).
However, some areas are predicted to experience low category rainfall of less than 50 mm/dasarian, predicted to occur in:
August III-2026: parts of Sumatra, Java, Bali, NTB, NTT, most of Kalimantan, Sulawesi, North Maluku, Maluku, Papua
September I-2026: southern Sumatra, Java, Bali, NTB, NTT, most of Kalimantan, Sulawesi, North Maluku, Maluku, parts of Papua
September II-2026: southern Sumatra, Java, Bali, NTB, NTT, most of Kalimantan, Sulawesi, North Maluku, Maluku, parts of Papua.
Forest and Land Fires in East Kalimantan
In the same statement released by BMKG, East Kalimantan Deputy Governor Seno Aji said that the regional government has prepared additional measures to control the threat of drought and forest and land fires that could still occur until the end of August 2026. He added that around 200 fire spots are currently monitored in East Kalimantan.
The status of forest and land fire handling in East Kalimantan remains at the Disaster Standby level and has not yet been raised to Emergency Standby.
Seno Aji also reminded each region to be aware of vulnerability and disaster conditions in their respective areas, so that they can immediately submit requests for assistance to BNPB if they meet the Emergency Standby criteria.