Indonesia
has a tropical climate with high temperatures and humidity year round, a wet
season and a dry season. The diverse topography and varying size of these
islands results in regional climatic variation. As a rule, inland areas are
cooler than coastal regions as they tend to be at higher elevations; many
islands are mountainous, the highest, snow-capped mountains exceeding 3000 m.
Bridging the equator, Indonesia receives little variation
in temperature from season to season; the wet season is only about 1°C hotter
than the dry season. Across coastal areas, where all of the traditional holiday
destinations are, the average high temperature rarely strays far from 31°C, and
the average low temperature is usually around 23°C. Humidity is high at all
times without exception. The first thing that hits you when you go to an
equatorial area like Indonesia
is the combination of heat and humidity; it instantly wraps itself about you
like a warm, wet tongue. The air feels thick in your lungs and sweat instantly
beads on your upper lip. These conditions become even more intense on entering
the rainforest and the risk of dehydration is high, though as you climb higher
the heat relents. For most, this is hard to acclimatise to and most find
air-conditioning a must at night time. However, there is something to be
recommended of fan cooled beach huts, with the sea breeze sneaking up through
the slats in the floor.
As Indonesia
is a tropical archipelago, rainfall can be expected at any time of year, but
the wet season, as its name suggests, generally sees a marked increase in
rainfall. There is great regional variation in terms of the length of each
season, and when they fall in the year, so rainfall levels for specific
locations should be checked before travelling. Some areas, for instance Ambon
and Medan, see a complete reversal of the
seasons, while others, such as Padang and Biak, see incredibly high rainfall all year with no
seasonal variation.
The wet season in the main tourist areas, for instance Jakarta, Bali, Lombok and most of Borneo,
generally lasts from November till April. During this season, the weather of
the islands is dominated by the north-western monsoon winds which bring huge
volumes of rain in torrential tropical storms. Heavy rainfall crashes down in
violent thunderstorms and can cause flash flooding and landslides. Aside from
being inconvenient for the traveller, these conditions can become dangerous and
the poorer communities often suffer great losses of every imaginable kind.
Every year sees fatalities caused by flooding with many more made homeless. Climate
change is causing these floods worsen each year. Due to the directionality of
the wind, northwest regions tend to receive higher rainfall; the islands
closest to Australia
actually have quite dry climates. This season is generally more overcast and
unpredictable. It still sees around six hours of sunshine but these hours are
frequently broken by short downpours. It is important for travellers to
remember that even when the sky is a heavy grey the UV index remains high, and
sun block should be worn at all times.
The dry season, from May till October, is not exceptionally
dry in most places. However, storms become shorter and occur less frequently
and the sun shines for around nine hours a day. While some feel there is no
need to avoid Indonesia or
the rest of Southeast Asia during wet season,
dry season is the accepted tourist season and with good reason. The sea is
calmer, the rain relents and the sun beats down; everything becomes easier and
more enjoyable from sunbathing to taking a boat trip to eating at a hawker
stall. The sea, which is always warm enough to swim in, presents visibility
conditions more favourable to snorkelling and scuba diving. While it is true
that days perfect for these activities happen during the wet season, the dry
season offers more.
Despite being surrounded by the sea, Indonesia is
not susceptible to hurricanes. However, Indonesia does have the more active
volcanoes than any other country, and is also prone to earthquakes. Java and Bali are the most active. The eruption of Indonesia’s Mount
Krakatoa in 1883 is perhaps the most
famous eruption of all time; it destroyed two thirds of the island, was heard
in Perth and sent thick clouds of volcanic dust
westward which played havoc with the weather all over Europe.
Now it is the clouds of smoke from Indonesia’s industrial factories
that interfere with the weather in surrounding areas. In 2004 the earthquake
off the west coast of Sumatra in the Indian Ocean
triggered the devastating tsunami, killing almost a quarter of a million
people, and 80,000 in Banda Aceh alone. While huge eruptions are rare, it is
important to check on volcano eruptions before travelling to Indonesia.
Indonesia’s climate can be attributed to its equatorial
location which keeps temperatures high with little seasonal variation; its
location in the Indian Ocean which means it is susceptible to monsoons; its
mountainous topography which creates temperate and alpine microclimates and
also traps the northwest monsoon winds making northwest regions wetter; and to
the varying size and location of the islands which changes each area’s
susceptibility to the moderating effects of the sea and to winds.
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