Indonesia’s meteorological agency BMKG has issued a weather advisory for Saturday 3 January, warning of widespread rain across much of the country with localised heavy falls and the potential for flooding. Although Tropical Cyclone Iggy is tracking away from Indonesian waters, its influence continues to fuel unstable conditions that may produce sudden and intense downpours.
Indonesia weather forecast and expected impacts
BMKG reported that Cyclone Iggy was located in the Indian Ocean south of West Java, with maximum winds around 40 knots and a minimum central pressure near 995 hPa. The system is moving southeast and is expected to be away from Indonesian territory within 24 hours. Despite its outward track, the cyclone is maintaining elongated bands of convergence and confluence from the southern coast of West Java to East Java, which help lift moist air and foster cloud formation.
Authorities also noted cyclonic circulations in the South China Sea north of Brunei Darussalam and in the Indian Ocean southwest of Lampung. These combined atmospheric disturbances increase the likelihood of convective cloud growth and locally heavy rainfall in several regions.
The most significant threats remain from heavy rain that can lead to flash floods, river flooding and urban waterlogging. BMKG singled out South Kalimantan and North Kalimantan as areas at elevated risk of flooding and standing water. Local emergency services are on alert and residents in low-lying and riverine areas have been advised to prepare for possible evacuations.
Public safety measures recommended by officials include securing loose items, avoiding travel through flooded roads, and keeping updated with the latest forecasts from BMKG. Urban drainage systems and river monitoring are expected to be key in mitigating impacts where heavy rain falls over short periods.
Regional outlook and city forecasts
BMKG provided a region-by-region outlook. In western Indonesia, Surabaya and Tanjung Selor may see thunderstorms, while Pangkal Pinang, Bandung and Banjarmasin are forecast to experience moderate rain. Much of Sumatra, Jakarta, Semarang, Yogyakarta, Palangkaraya and Samarinda may expect light rain, and areas such as Aceh, Tanjung Pinang, Serang and Pontianak are likely to be cloudy to heavily cloudy.
In the east, Palu faces a risk of thunderstorms, with Mamuju, Jayawijaya and Merauke forecast to have moderate rain. Large parts of Sulawesi, the Maluku islands, the North Maluku archipelago and much of Papua are expected to see light rain. Denpasar, Mataram and Kupang are predicted to be mostly cloudy.
BMKG emphasised that even areas forecast for light rain should remain vigilant because conditions can evolve rapidly when multiple atmospheric systems interact. Localised heavy showers may develop with little notice, increasing the risk of flash floods and landslides in susceptible terrain.
Residents are encouraged to follow updates from BMKG and local authorities, prepare emergency kits, and have evacuation plans ready if they live in flood-prone zones. Infrastructure managers are advised to monitor drainage and river levels, and transport operators should anticipate delays or route changes where flooding occurs.
While Cyclone Iggy is expected to move away from Indonesian waters within a day, its residual influence means that unsettled weather and elevated rainfall risks will persist. Continued monitoring and a readiness to respond remain essential as the country contends with the immediate hazards posed by heavy rain and possible flooding.
Key Takeaways:
- Indonesia weather forecast warns of widespread rain with varying intensity across the archipelago.
- Cyclone Iggy south of West Java is moving away but continues to cause convergence and heavy showers.
- BMKG highlights flood and waterlogging risks in South and North Kalimantan and urges public vigilance.
