Rainy Season in Bali and Nusa Tenggara Predicted to be Delayed, Peak Period Announced
The rainy season in Bali and Nusa Tenggara is predicted to arrive later than normal. The Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG) estimates that parts of Bali, West Nusa Tenggara (NTB), and East Nusa Tenggara (NTT) will only enter the rainy season between January and February 202 Im27.
According to reports, the peak of the rainy season in Bali is predicted to occur in January and February, while the NTB and NTT regions are also expected to experience their peak during the same period. This prediction is part of the 2026/2027 rainy season forecast released by BMKG. The simultaneous occurrence of the El Niño and Indian Ocean Dipole (IOD) phenomena is cited as one of the factors causing the delayed rainy season.
“The combination of the El Niño and IOD phenomena occurring simultaneously exacerbates and extends the drought period in most parts of Indonesia, resulting in a delayed and shorter rainy season,” said the Head of BMKG, Teuku Faisal Fathani, during a press conference.
In addition to the delayed start, BMKG Deputy for Climatology, Ardhasena Sopaheluwakan, stated that the onset of the rainy season across Indonesia will not be simultaneous. Most regions will begin their rainy season in November 2026 and December 2026.
“The 2026/2027 rainy season is generally normal across 510 ZOM (69.76% of Indonesia’s land area). Attention is required for 147 ZOM (18.55% of Indonesia’s land area) as rainfall will be wetter than usual, while only 42 ZOM (11.69%) are predicted to be below normal or drier,” said Ardhasenia.
According to recent BMKG social media updates, 61.08% of the land area, or 529 ZOM, will enter the rainy season later than normal. Meanwhile, 2.15% of the region (26 ZOM) will enter the rainy season at the same time as normal, and only 1.12% of the region (11 ZOM) is predicted to enter the rainy season earlier than normal.
BMKG predicts that the peak of the 2026/2027 rainy season will largely occur in December, covering 36.94% of the land area. Subsequently, 25.68% of the region will experience the peak in January, and 16.79% in February.
The breakdown of the rainy season peaks by region is as follows:
- December:
Most of Sumatra
Most of Kalimantan
Parts of North Sulawesi
Southern coast of Gorontalo
Small parts of Central Sulawesi
Most of West Sulawesi
Small parts of Maluku
Western part of Southwest Papua
Small parts of West Papua
Northern Papua
Eastern part of Central Papua
Western part of South Papua.
- January:
Southern Riau
Central Riau Islands
Small parts of Jambi
Northern Bengkulu
Bangka Belitung Islands
Western South Sumatra
Northern Lampung
Parts of Java
Central Bali
Western NTB
Parts of NTT
Parts of West Kalimantan
Most of Central Kalimantan
Small parts of East Kalimantan
Most of South Kalimantan
Parts of Sulawesi
Small parts of North Maluku
Western Maluku
Parts of Papua.
- February:
Central Lampung
Most of Java
Most of Bali
Most of NTB
Most of NTT
Southern part of West Sulawesi
Parts of South Sulawesi
Southern part of Southeast Sulawesi
Parts of Maluku
Most of Papua Island.
According to BMKG, a region is considered to have entered the rainy season if rainfall reaches 50 mm or more within one ‘dasarian’ (a 10-day period), followed by at least two consecutive ‘dasarian’. The start of the rainy season can occur earlier, at the same time, or later than the normal climatological average of the last 30 years.