Bali month by month, at a glance
Figures for Denpasar, 1991-2020 series. It rains considerably more in the highlands. Hover over each month.
In Denpasar the highest mean maximum of the year is 31.6 °C, in November, and the lowest is 29.0 °C, in July. Two and a half degrees of range across twelve months. The minima move even less: between 23.8 and 25.3. With numbers like that, asking when the temperature is best in Bali has no answer, because there is no variation to choose from. The useful question is a different one: how much water falls, and how much of it is in the air.
The key moments at a glance
388.4 mm over 18.8 days in January and 298.7 mm in February, humidity at 82 and 84 per cent. The least sun of the year and the worst heat to bear, even though the maximum stays at 30.9 °C.
Rain drops from 72.8 to 29.7 mm and humidity falls from 65 to 50 per cent, the year's low. July is also the coolest month: a mean maximum of 29.0 °C.
16.1 mm over 1.9 rainy days and 277.4 hours of sun. Meteorologically the best month of the year; it also coincides with northern-hemisphere holidays and peak occupancy.
281.1 hours of sun, the annual maximum, with only 67.9 mm over 4.8 days. The crowds have thinned and the monsoon has not returned.
01 The thermometer is no use for deciding
The figures are for Denpasar, 1991-2020 series. The mean maximum runs from 29.0 in July to 31.6 in November; the minimum from 23.8 in August and September to 25.3 in November and December. In practical terms the day is always around thirty degrees and the night around twenty-four. In February and in August alike.
What does change, and sharply, is relative humidity: 50 per cent in July against 84 per cent in February. That is the difference the body registers. Thirty degrees at half humidity is a comfortable day for walking; thirty degrees at 84 per cent is an afternoon in which any effort costs. When someone says it is «less hot» in Bali in August, they are describing the hygrometer, not the thermometer.
02 The rain does move, and on a different scale
The island receives 1,742.2 mm a year spread over 107.6 rainy days, and that total is very unevenly distributed. January takes 388.4 mm over 18.8 days. August takes 16.1 mm over 1.9 days. That is a ratio of twenty-four to one between the wettest month and the driest: where the thermometer moves by 8 per cent, the rain gauge multiplies by twenty-four.
The cause is the west monsoon, which unloads roughly from October to April and concentrates the bulk between December and March. It is worth understanding how that water arrives. It is not continuous drizzle: it is intense downpours, often in the afternoon, that can leave the whole morning clear. A January in Bali does not mean seven days under rain; it means most days will lose a stretch and that clothes will not dry.
The monsoon's other effect is less obvious and matters more to the trip: the sea. With westerly swell and wind, fast-boat crossings to Nusa Penida or the Gilis are frequently cancelled, and underwater visibility drops because of runoff. The season does not only decide whether it rains; it decides whether you can leave the island.
03 The dry season and what it brings besides sun
From May to October the island changes regime. May leaves 72.8 mm over 6.5 days, June 50.8 over 4.7, July 29.7 over 3.3 and August 16.1 over 1.9. Sunshine hours rise in parallel: 264.6 in May, 277.4 in August and 281.1 in October, which is the annual maximum.
That period also brings offshore wind on the south-west coast, which is what tidies the waves and explains why the surf season at Uluwatu and around it runs from May to September. On the east coast the opposite applies, which is why the best months for diving at Tulamben and Amed do not line up exactly with the best months for surfing in the south-west.
There is a matter of altitude that gets forgotten. The figures above are for Denpasar, at sea level. In the highlands — Munduk, Bedugul, the lake district, above a thousand metres — it rains a good deal more, the nights are cool and cloud builds almost daily even in August. If the plan is a mountain one, the dry season is less dry than the table promises.
04 The day that cancels the calendar
There is one date worth checking before buying a ticket. The Balinese new year, Nyepi, falls in March, changes date each year and stops the entire island for twenty-four hours: no fire or light visible from outside, no work, no movement in the street and no entertainment. The rule applies to visitors as well.
In practical terms Ngurah Rai international airport stays closed for that period, with no arrivals or departures, and the mobile operators suspend data service. Hotels keep running, but guests are asked not to leave the grounds. It is not a minor inconvenience if it crosses your arrival or departure date: on that day you simply cannot fly.
05 What to choose, concretely
If the aim is reliable weather, the answer is June, July and August, in that order of thermal comfort. July and August combine the lowest humidity of the year, minimal rain and the most sunshine; the cost is that they coincide with northern-hemisphere holidays and the highest prices.
If the aim is a balance between weather and crowds, May and October are better. May enters the dry season with the island still green from the monsoon; October is the sunniest month of the year, with rain still low and the high season already over.
And if January or February are your only options, it is not lost, but the plan changes: fewer boats and fewer crossings, more inland, and an acceptance that the afternoon belongs to the rain. The island in full monsoon is at its visual best — terraces full, saturated green, waterfalls running — and at its logistical worst. It is a trade, not a sentence.
