TEMPO.CO, Jakarta - Rain has returned to parts of Greater Jakarta in recent days, raising questions about why heavy downpours are still occurring even as Indonesia enters the dry season and the El Niño climate pattern continues to strengthen.
Data from the Meteorology, Climatology, and Geophysics Agency (BMKG) shows that several areas in the Jakarta metropolitan region recorded significant rainfall on Monday, June 22, 2026. The highest rainfall intensity was recorded in Kelapa Gading, North Jakarta, at 87.8 millimeters.
The rainfall was widespread across Jakarta and surrounding areas. A day earlier, on June 21, moderate rain was concentrated mainly in parts of Bogor and Tangerang. Similar conditions were also observed on June 20.
The phenomenon has not been limited to the capital region. BMKG recorded heavy rainfall in several provinces between June 19 and June 21, including West Sumatra, Aceh, North Sumatra, Central Kalimantan, West Sulawesi, East Java, and West Kalimantan.
Why Is It Still Raining During the Dry Season?
According to BMKG, the ongoing rainfall is being driven by several atmospheric factors that continue to support cloud formation and precipitation across parts of Indonesia.
One of the main contributors is the activity of Equatorial Rossby Waves around Sumatra. BMKG also identified Kelvin Wave activity affecting areas of Sumatra and Kalimantan, while cyclonic circulation in the western Indian Ocean off Sumatra has further enhanced rainfall potential.
These weather systems can increase atmospheric moisture and trigger the development of rain-bearing clouds, even during the dry season.
"As the dry season expands across parts of Indonesia, the possibility of significant rainfall still needs to be anticipated, particularly in regions influenced by these atmospheric dynamics," BMKG's Directorate of Public Meteorology said in a statement on June 22.
What Is the Weather Outlook?
BMKG expects most parts of Indonesia to experience low to moderate rainfall during the third ten-day period, or dekad, of June 2026.
Moderate rainfall remains likely in central and northern Sumatra, western and northern Kalimantan, parts of Sulawesi, Maluku, and Papua. Overall, however, the agency said the dry season is expected to continue expanding across much of the country.
Areas Advised to Remain Alert
BMKG warned that several weather systems could continue influencing conditions over the coming week.
The propagation of Kelvin Waves from Sumatra, Kalimantan, North Sulawesi, North Maluku, and the southwestern coast of Papua is expected to support the growth of convective clouds, increasing the likelihood of rainfall in some regions.
The situation may be reinforced by cyclonic circulation patterns in the western Indian Ocean and the Makassar Strait, which can create zones of wind convergence and atmospheric instability.
BMKG said relatively strong atmospheric instability remains present in several provinces, including Aceh, Riau, South Sumatra, Central Kalimantan, South Kalimantan, West Sulawesi, Southeast Sulawesi, North Maluku, and Papua.
As a result, residents in those areas are advised to remain vigilant for the possibility of rain, despite the ongoing expansion of the dry season across Indonesia.
Read: Rain Potential Remains in West Java Despite Dry Season
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