How Bali rainfall is measured: districts, rainy days and extremes
Bali’s rainfall cannot be represented by one island-wide number: official 2025 records show sharp differences between districts, months, rainy-day totals and daily extremes.
By Mukmin John
Editor: Mursyid Sonsang
· 2 min read
Bali’s rainfall is not uniform across the island or from month to month. Official BMKG data for 2025 recorded the year’s highest daily rainfall at 385.5 mm on 10 September, while the wettest monthly total reached 806.5 mm in September in southern Karangasem, showing why rainfall data must be read by place, period and measurement.
Why does rainfall vary across Bali?
BMKG divides Bali into rainfall zones and reports observations from weather stations and cooperating rain gauges. Its 2025 annual climate bulletin presents monthly rainfall, rainy-day totals, monthly maximum rainfall and maps, rather than one island-wide figure.
The variation is visible in the monthly records. In July 2025, the highest monthly rainfall was 813.0 mm in southern Karangasem’s Selat district, while some parts of Buleleng, Karangasem and Klungkung recorded 0–20 mm, according to BMKG, 2025.
Which month recorded the heaviest rainfall?
September 2025 produced the highest monthly total cited in BMKG’s annual bulletin: 806.5 mm with 16 rainy days in southern Karangasem’s Sidemen district, according to BMKG, 2025.
That monthly figure is a local observation, not a total for the whole province. BMKG’s September bulletin also recorded rainfall ranging from 0.0 to 806.5 mm across Bali’s climate zones, according to BMKG, 2025.
What was Bali’s highest daily rainfall in 2025?
The annual bulletin recorded 385.5 mm on 10 September 2025 as the largest daily rainfall event at the Bali climatology station during the year, according to BMKG, 2025.
Separate zone-based reporting recorded a September daily maximum of 390.0 mm in southern Badung’s Mengwi district, according to BMKG, 2025. The difference reflects different observation points and reporting datasets, so the figures should not be combined.
How should residents and visitors read the numbers?
A monthly total measures accumulated rainfall over a month; a rainy-day count measures the number of days with rain; and a daily maximum identifies the largest amount recorded in one day. These are different indicators and answer different questions.
- For accumulated wetness, use the monthly total.
- For how often rain occurred, use rainy days.
- For short-duration intensity, use the daily maximum.
BMKG’s annual bulletin also recorded daily rainfall above 50 mm on seven dates in 2025, including 385.5 mm on 10 September, according to BMKG, 2025. The Bali provincial Satu Data platform identifies climate and other sectoral information as part of the province’s integrated public-data system, according to the Bali Provincial Government, 2026.
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