Why a Weather Model Says It Rains 25 Days in Bali in August (and What a Rain Gauge Says)

Does it really rain 25 days in Bali in August?

No. Canggu's August rain days: about 4 by our count, 2 to 4 by the airport gauge, and 25 only if you count drizzle from a weather model. Counted straight from a weather model, Canggu in August comes out at around twenty-five wet days, but that number counts drizzle, not rain. A rain gauge at the airport at Denpasar, 15 km from Canggu, records 2 to 4 days with rain in a typical August. We used to show the high number ourselves. Since 29 October 2026 Canggu shows about 4 rain days in August, and the rest of this page explains why the two numbers are so far apart and why we trust the lower one.

Read the rain-days column as a count: in Canggu, about 4 of August's 31 days. For the rain across the whole year, with the wet and dry seasons, see the Canggu chart further down.

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Where does the 25 come from?

Our own numbers came from a weather model, not a rain gauge, until 29 October 2026. A model such as the one behind the Open-Meteo archive is a weather forecast rerun over the past. It gets temperature, wind and humidity right because it takes in satellite, station and balloon readings. Its rain, though, comes out of its own physics.

Two things make it count far too many wet days in the tropics:

1. One value per box. The model gives one number for a grid box roughly 9 to 25 km across. A storm 3 km wide that drops a lot of rain on one village is averaged over the whole box, so the box shows a little rain instead of a lot in one place. In the tropics there is a shower somewhere in a box almost every day, so the box counts as wet almost every day.
2. Storms are too small for the model. It estimates them with rules of thumb that trigger rain too often and too lightly: many days of drizzle, too few downpours.

If a rain day is then any day above a trace of rain, the count runs far above what anyone standing in Canggu experiences. The monthly total in millimetres holds up much better than the day count, because the model cannot invent or lose much water. The damage is in the count of days.

What counts as a rain day?

A day with real rain, not drizzle. Weather services count a rain day from one millimetre on a gauge reading. On model data that line still gives too many days, so we tested several.

We compared the model's daily rain with 49 rain gauges near our destinations, day by day, 18 of them in the tropics, and scored each line against the gauge's rain days. The old line, any trace of rain, was off by 10 rain days a month on average. A single two millimetres line everywhere was better but still too wet in the tropics. The line that came closest uses the latitude: four millimetres in the tropics and two millimetres everywhere else. It is off by 2 days a month on average (3 in the tropics, 1 elsewhere), and it needs nothing but the place's coordinates, so it works for every destination, including the ones with no gauge nearby.

Outside the tropics we typically land within about a day a month of the gauge. In Bali we are within a few days. That is the honest range: a rain day count is an estimate, and we say so under every table.

What does that change for Bali?

The picture matches what people who live there say. August is dry, with a few short showers. In January the rain days move to the other end of the scale.

Canggu's year looks like this, with the rain line over the temperature band:

Averages 2015-2025 · Source: Open-Meteo · How we measure

In August that is about 4 rain days and 56 mm; in January about 19 rain days and 313 mm. Uluwatu is drier than Canggu in August, with 17 mm, and Ubud is wetter, with 118 mm. Our Canggu, Uluwatu and Ubud comparison goes through all twelve months, and the Bali by area guide shows how the season runs across the island.

For a nomad this decides two things. First, whether to plan around the rain at all: in the dry season you do not need to, apart from keeping a rain jacket in the bag. Second, how much to trust any "rainy days" number you read; our guide on weather for digital nomads explains how to read rain-day counts, forecasts and climate averages. A count above 20 wet days in a month called dry is almost certainly counting drizzle.

What else is different about how we do it?

We use the best source for each number. Temperature and cloud come from Open-Meteo, which uses ECMWF data. Rain totals in millimetres come from satellite and rain-gauge data (CHIRPS) where it passes our test against gauges, and from the model where it does not. Our test showed that the satellite source matches the airport gauge for Uluwatu through the dry season, but reads Canggu's dry-season rain two to three times too wet, so Canggu keeps the model's totals.

Every number in a guide is checked against the stored data before it goes live. This does not make any figure exact: Bali has sharp local differences, and the hills above Ubud can be wet while the coast is dry. Use the numbers to compare places and months with each other, which is what they are good for, and not to promise a dry afternoon. For the wet months, the Bali rainy season guide covers how nomads handle them.

Weather data: Open-Meteo (CC BY 4.0) and ECMWF. Rain totals: CHIRPS, Climate Hazards Center, UC Santa Barbara.