Jakarta, domclub Indonesia
—
Meteorology, Climatology and Geophysics Agency (
BMKG
) said that high rainfall has the potential to flush several areas ahead of the Christmas 2025 and New Year 2026 (Nataru) periods, one of the causes of which is
La Niña
.
Head of BMKG Teuku Faisal Fathani said that in the 2025/2026 Christmas period there would be a number of active atmospheric phenomena, including the Asian Monsoon, Madden Julian Oscillation (MJO), atmospheric waves, as well as the potential for cyclone seeds or tropical cyclones.
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“The influence of weak La Nina and negative Indian Ocean Dipole (IOD) also plays a role in increasing the potential intensity of rainfall, especially in the second week of December 2025 to the first week of January 2026,” he said in a statement, Monday (8/12).
Faisal explained that high to very high rainfall is predicted to occur in a number of areas, with a range of around 300 to 500 millimeters per month in the period December 2025 to January 2026.
“Areas that have the potential to experience these conditions include Java, Bali, Nusa Tenggara, parts of South Sulawesi and South Papua. Meanwhile, most of Kalimantan is climatologically in the rainy season throughout the year,” he explained.
He said that the peak of the rainy season in the Lampung, Bengkulu, Java, Bali and Nusa Tenggara regions is estimated to occur from January to February, while for most of the Sumatra region, except Bengkulu and Lampung, the peak of the rainy season will be in December.
This condition is considered to need attention in planning and strengthening anticipatory steps ahead of the year-end holiday period.
Furthermore, active Rossby and Kelvin waves are said to increase the growth of rain clouds in southern Sumatra, Java and Papua.
Meanwhile, MJO contributes to increasing the potential for high to very high intensity rain, especially in Java, Kalimantan, as well as parts of Sulawesi and Papua.
During the Christmas period, cyclone seeds were also observed around Indonesia which were continuously monitored by the BMKG’s Tropical Cyclone Warning Center (TCWC).
Responding to these weather conditions, BMKG has issued an early alert warning through the provincial coordinator or the Regional Center for Meteorology, Climatology and Geophysics, especially in areas potentially affected by increased rainfall.
Some of these areas are North Kalimantan, North Sulawesi, Bengkulu and Lampung.
BMKG also noted the potential for tidal flooding in mid-December, especially in the Banten, Jakarta, north and east coasts of Java, as well as several areas in the Riau Islands and Kalimantan, including the North Coast of Jakarta, Banten and the Pantura of West Java.
As a mitigation measure, BMKG together with BNPB carried out Weather Modification Operations in a number of areas, including Aceh, North Sumatra, West Sumatra, West Java and East Java.
This operation is aimed at supporting efforts to overcome and reduce the risk of hydrometeorological disasters.
Transportation
In the air transportation sector, BMKG detected the potential for Cumulonimbus cloud growth which needs to be watched out for during the Christmas period.
In December 2025, flight routes at risk of being affected include the Natuna Sea, southern Karimata Strait, Makassar Strait, Sulawesi Sea, Banda Sea and northern Papua.
Meanwhile, in January 2026, the potential for Cumulonimbus clouds is predicted to occur on flight routes around the Indian Ocean west of Sumatra to the south of Nusa Tenggara, Java Sea, Makassar Strait, Banda Sea, Arafura Sea and the Papua region.
For the maritime transportation sector, BMKG estimates that sea waves in the moderate category, ranging from 1.25 to 2.5 meters, will occur in the western and southern waters of Sumatra, the Sunda Strait, the southern waters of Java to East Nusa Tenggara, the northern waters of the Anambas and Natuna Islands, and the northern Pacific Ocean from Halmahera to Papua.
(lom/dmi)
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