Climate of Indonesia

Climate of Indonesia

Where is the country of Indonesia located? Indonesia is located almost around the equator in southeastern Asia. This former Dutch colony is almost entirely tropical. With the exception of the highest spots in the mountain areas except for Papua and Borneo, almost all large islands have a tropical rainforest climate (type Af according to the Köppen-Geiger climate classification ). The smaller islands east of Java and some parts of Java itself have a tropical monsoon climate. This is because in these regions there is a clearer distinction between a wet and a drier season, with the driest month remaining below 60 millimeters per month in terms of precipitation.

Bergen & the volcano

Characteristic for Indonesia are the many volcanoes and mountains, which means that there are enormous differences in height on some islands. In Papua you will find the mountain Puncak Jaya, which with a height of 4884 meters is the highest point in the region and is one of the few places around the equator where even snow and ice can be found. The total glacier surface has decreased in recent decades. On the list of the 100 highest mountain peaks in the world, there are no fewer than 10 from Indonesia. Puncak Jaya is number nine on this list. The mountainous landscape has a clear influence on Indonesia’s climate. On the highest peaks it is first of all cooler than in the lowest areas. On the highest peaks of Papua (the former Irian Jaya) there is even eternal snow.

For the rest of Indonesia, the location and the season determine where and how much rain falls. The windward side of a mountain is the side where the wind comes in. With a trade wind from the northeast, the windward side is the northeast side of the mountain. In a southeast trade wind, the wind comes almost continuously from the southeast, making the southeast side of the mountains the windward side. The windward side of a mountain almost always catches more precipitation than the leeward side. This is partly due to rising rains and the fact that longer chains of mountains can stop rain depressions, as it were. The depressions rain down, as it were, empty against the mountain side, so that you get considerably less rain on the leeward side of the mountain.

Rainy seasons

There is no shortage of rain in Indonesia. On average, there is 1500 to 2500 millimeters of rain per year, but some parts of Indonesia are considerably wetter. The mountains on Irian Jaya (Papua) in particular receive much more rain on the windward side and on the other islands it is mainly the eastern and northeastern slopes that receive quite a bit of rain. Indonesia has a rainy season (monsoon), which starts in September (west) or October. This rainy period, in which fairly large amounts of precipitation can fall, lasts on average until March. From April it will be drier in almost all of Indonesia. This is when the northeast trade winds turns and turns into trade winds coming from the southeast. During the drier period, the north of Indonesia still has to deal with a small rainy period in the months of June and July. August and September are considerably drier, especially in the south, as a southeasterly current from Australia brings dry air. In October, the south-east trade wind changes into a north-east trade mark, with the amount of precipitation increasing considerably. Most rain falls in the form of (heavy) showers, which are often accompanied by thunderstorms. The islands of Borneo, Java and Sumatra are good for no less than a hundred days with thunderstorms per year.

The hurricane

Due to its location around the equator, most of Indonesia falls just outside the supply route of hurricanes, which are referred to here as cyclones. A very large part of Indonesia lies within the Intertropical Convergence Zone (the ITCZ) for a reasonable part of the year. This is the area where the cyclones (hurricanes) arise when the seawater temperature has risen to about 27 degrees. This zone is not a fixed area, but shifts during the year. The chance that Indonesia itself will be hit by a hurricane is quite small. Most hurricanes find their path just south of Indonesia and move through Australia to the Indian Ocean. The greatest chance of experiencing a hurricane in Indonesia is on the islands of Timor, Roti, Sumba and Papua. On the major islands of Borneo, Sulawesi, In Java and Sumatra, the chance that a hurricane will pass over is virtually nil. However, there can be considerable nuisance due to rain and wind that is supplied by active fronts in the region.


Indonesia is a warm country, where – with the exception of the highest areas – tropical temperatures are measured almost continuously of about 29 to 33 degrees during the day and about 23 degrees at night. There is little variation in temperature throughout the year. During our winter, the south of Indonesia is slightly warmer than the north; halfway through the year this was reversed. Extreme heat in Indonesia is limited to a maximum of 37-38 degrees. In combination with a high relative humidity, this feels very stuffy and oppressive and the perceived temperature rises to well above forty degrees.


The power of the sun is great in Indonesia. In the north, which is around or just below the equator, the highest possible sun strength of 11 applies almost all year round. In June and July, the sun strength in the southern half of Indonesia can be slightly lower. This is for all times when it is quite cloudy. For all skin types, applying a high factor sunscreen is necessary to avoid the risks of sunburn or worse.

Climate figures

The figures below are based on long-term average climate statistics. The temperatures are displayed in degrees Celsius (°C).

Maximum temperature Minimum temperature Hours of sunshine per day Days of rainfall per month Water temperature
January 30℃ 23℃ 4 24 28℃
February 31℃ 23℃ 6 23 28℃
March 32℃ 23℃ 7 26 29℃
April 33℃ 23℃ 8 18 30℃
May 33℃ 23℃ 8 13 29℃
June 32℃ 23℃ 8 14 29℃
July 33℃ 22℃ 9 16 29℃
August 33℃ 22℃ 9 17 29℃
September 33℃ 23℃ 9 16 29℃
October 33℃ 23℃ 8 19 29℃
November 33℃ 23℃ 7 24 29℃
December 32℃ 23℃ 6 25 29℃

Best time to visit Indonesia

Do you want to know when is the best time to travel to Indonesia? You can determine the best time to travel to a destination based on the weather and climate. In addition, there are other factors that are not directly related to the weather and that can influence the best travel periods for a travel destination. Think, for example, of holidays or festive periods, which makes traveling more interesting or not, because daily life comes to a standstill as a result. Indonesia is located around the equator and has a tropical climate. Daytime temperatures are around thirty degrees or slightly higher throughout the year. It is somewhat cooler in the higher areas and especially in Papua where the highest mountain peaks are even cold with eternal snow and ice. In practice, however, you will almost always have to deal with tropical weather conditions in which a bright sun alternates with sometimes heavy rain and thunderstorms. During the monsoon period, which runs from September/October to the beginning of April, the number of precipitation days increases and the intensity of the rainfall also increases. At the end of the monsoon, the humidity has increased to fairly high percentages (just above eighty percent). It feels clammy and stuffy almost everywhere, especially during that period. There are areas in Indonesia for which there is actually no best time to travel. These are the (parts of) islands with a tropical rainforest climate and where considerable amounts of rain fall throughout the year. These are, for example, the southern coastal strip of Sumatra, a large part of Indonesian Borneo and most of New Guinea.

Best months

If you leave out the above areas of Indonesia, the best time to travel to Indonesia is the period from June to September . This is the drier and sunniest period in a fairly large part of Indonesia.

Beach holiday

If you want to book a beach holiday or round trip to Indonesia, it is best to do so during our summer season. The months of August and September are the best period for a sun holiday to Indonesia. July is also fine, but a little wetter. The same applies to June, which is a good alternative for those who want to avoid the expensive summer holiday period. Indonesia is considerably less suitable as a winter sun destination. If you want to seek out the sun and warmth in Indonesia during our winter, you will sooner have to deal with changeable weather with a fairly high chance of a rain shower. You will get the desired heat in the winter. Count on maximum temperatures that are on average between 30 and 34 degrees. The relatively high relative humidity makes it feel stuffy.