Heavy Rain Warning for Several Regions in Indonesia This Week<\/p>\n
Reporter<\/p>\n
September 30, 2026 | 07:07 pm<\/p>\n
TEMPO.CO, Jakarta - Indonesia\u2019s Meteorology, Climatology and\nGeophysical Agency (BMKG) has issued an early warning for potential\nheavy to very heavy rain in several parts of the country over the next\nweek.<\/p>\n
According to BMKG\u2019s weather forecast for September 29 to October 5,\n2026, residents in Aceh, North Sumatra and West Java have been advised\nto remain alert for heavy to very heavy rain. Bengkulu is also under an\nalert for September 29 to October 1, while the warning applies to Papua\nHighlands from October 2 to 5.<\/p>\n
Why Is Heavy Rain Expected?<\/p>\n
BMKG said weather conditions across much of Indonesia from late\nSeptember to early October would remain influenced by a very strong El\nNi\u00f1o, although regional atmospheric dynamics could increase\nrain-producing cloud activity in some areas.<\/p>\n
From September 27 to October 4, the Madden-Julian Oscillation (MJO)\nis forecast to move across the western Indian Ocean off Sumatra,\naffecting West Sumatra, the Mentawai Islands, Riau and South\nSumatra.<\/p>\n
Meanwhile, Equatorial Rossby and Kelvin waves are expected to be\nactive simultaneously across parts of Sumatra and surrounding waters,\nincluding the waters north of Sabang in Aceh and the western Indian\nOcean off Aceh.<\/p>\n
Areas Affected by Atmospheric Waves<\/p>\n
Across Bengkulu, Lampung, Banten, West Java, Jakarta, Central Java\nand waters off southern Central Java, Equatorial Rossby wave activity is\nexpected to have a stronger influence.<\/p>\n
These atmospheric waves can create conditions favorable for the\ngrowth of rain clouds in the areas they pass through.<\/p>\n
BMKG also forecast slowing and shifting wind patterns in parts of\nAceh, the Riau Islands, West Kalimantan, Central Kalimantan, East\nKalimantan and West Papua. These patterns could increase the convergence\nof air masses and strengthen rain-cloud formation.<\/p>\n
Local Atmospheric Conditions<\/p>\n
At the local level, strong atmospheric instability is also expected\nin parts of northern and central Sumatra, West Kalimantan, Central\nKalimantan, Central Sulawesi and parts of Papua.<\/p>\n
Such conditions can intensify the upward movement of air and the\ndevelopment of convective clouds, particularly when sufficient moisture\nis available.<\/p>\n
\u201cThus, although global climate dynamics generally continue to limit\nrain-cloud formation across much of Indonesia, regional and local\natmospheric influences can still trigger increased rainfall activity in\ncertain areas,\u201d BMKG\u2019s Directorate of Public Meteorology said in a\nstatement released on September 28, 2026.<\/p>\n
Read: BMKG Warns of Local Downpours Despite Dry Season<\/p>\n
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