When Will Rain Drench Kalimantan After Severe Fires? Here's What BMKG Says
The Meteorology, Climatology and Geophysics Agency (BMKG) forecasts that most parts of Indonesia will still experience dry conditions this week and into next week. Even so, a number of regions still have the potential to be drenched by locally moderate to heavy rain.
BMKG conveyed the forecast through its official Instagram account in information on Indonesia’s Rain Potential for the Coming Week for the period 21-27 August 2026.
BMKG explained that Indonesia’s current weather conditions are still dominated by the dry season. Based on analysis of the first ten-day period of August 2026, as many as 535 Seasonal Zones (ZOM), or around 76.5% of Indonesia’s territory, have entered the dry season.
These conditions have caused low-category rainfall to dominate 90.79% of Indonesia’s territory. As many as 87.28% of areas are also experiencing below-normal rainfall characteristics.
BMKG linked the dry conditions to the El Niño phenomenon, which is at a very strong intensity, coupled with the Indian Ocean Dipole (IOD) being in a positive phase. Both phenomena reduce the supply of water vapour to Indonesian territory and strengthen drier atmospheric conditions.
The impact is also visible from the increasing incidence of forest and land fires in several regions. Based on monitoring of Himawari-9 satellite imagery on 19 August 2026, BMKG detected smoke distribution in several areas of central and southern Sumatra as well as Kalimantan, with some of the smoke carried by wind and spreading to surrounding areas.
Rain Still Potentially Occurring
BMKG forecasts that around 86.62% of Indonesia’s territory will be dominated by low-category rainfall, namely 0-50 mm per ten-day period, in the third ten-day period of August 2026.
These areas include most of Java, Sulawesi, Kalimantan, South Sumatra, the Bangka Belitung Islands, Lampung, Bali, West Nusa Tenggara, East Nusa Tenggara, Maluku, North Maluku, West Papua, and Southwest Papua.
Meanwhile, around 13.38% of other areas are forecast to experience medium-category rainfall of 50-150 mm per ten-day period. These areas include parts of Aceh, North Sumatra, West Sumatra, Riau, Jambi, Bengkulu, Central Papua, Papua, Highland Papua, and South Papua.
BMKG said a number of atmospheric disturbances and dynamics can still increase the chance of rain even though conditions are generally still dry.
Kelvin waves and Equatorial Rossby waves are forecast to be active in several areas of Sumatra, Kalimantan, Sulawesi, North Maluku and the Pacific Ocean north of Papua. These phenomena can increase convective activity and support the formation of rain clouds.
Rain potential is also strengthened by the presence of a low-pressure centre in the Pacific Ocean north of Papua, cyclonic circulation in the Makassar Strait, and the formation of convergence and confluence areas in several parts of Indonesia.
Areas with Rain Potential for 21-23 August 2026
For the period 21-23 August 2026, BMKG said Indonesia’s weather will generally be dominated by clear and cloudy conditions to moderate rain.
BMKG has set a Watch status for moderate to heavy rain for four regions, namely North Sumatra, West Sumatra, North Kalimantan, and Papua.
Meanwhile, BMKG has not designated any regions in the Advisory category for heavy to very heavy rain or Warning for very heavy to extreme rain for that period.
BMKG also warned of potential strong winds in Aceh, East Java, South Kalimantan, East Nusa Tenggara, South Sulawesi, and North Maluku.
Areas with Rain Potential for 24-27 August 2026
BMKG revealed that weather conditions during that period are generally dominated by clear and cloudy conditions to heavy rain.
BMKG has set a Watch status for moderate to heavy rain for Aceh, West Sumatra, and Riau.
Meanwhile, an Advisory status for heavy to very heavy rain has been set for West Sumatra.
Warnings for potential strong winds apply to Lampung, Banten, South Kalimantan, and South Sulawesi.