The best time to visit Sumatra, Indonesia, is during dry season, which falls roughly between February and October in North Sumatra, and March to November in South Sumatra. With less rain, bad roads are easier to navigate, smaller islands are easier to access by boat across calmer seas, and the conditions are better for trekking.
If you want to socialise with other backpackers, aim to travel to Sumatra during high season in June, July, and August. But don’t worry if you aren’t a fan of crowds; outside of tourist hotspots like Bukit Lawang, Sumatra is rarely crowded with foreign tourists, even in peak months.
Really, there’s no such thing as a “bad” time to visit Sumatra; wet season has the benefit of slightly cooler temperatures, and there’s nothing quite as invigorating as the almost daily late afternoon thunderstorms that pass through many areas. Outdoor activities are doable year round, and in general, the temperatures don’t differ dramatically throughout the year.
If you’re planning a trip and wondering about the best time of year to visit Sumatra, you’ll need to consider what areas you’re going to, what activities you want to do, and factor in things like public holidays and weather.
We’ve got you covered with details of everything you need to know, so read on and start planning your adventure!
Climate in Sumatra
Sumatra lies in an equatorial zone. In fact; the equator passes directly through the island, virtually cutting it in half.
What this means is a tropical climate with high rainfall and humidity but little variation in temperature. Throughout the year, the temperatures only vary by a few degrees; the average temperature of the whole island sits at 27-28 degrees Celsius (80-82 degrees Fahrenheit) year-round.
Being smack bang on the equator also means that day and night length are consistent throughout the year. There are approximately 12 hours of daylight every day of the year, from around 6-6:30 am to 6-6:30 pm.
If you’ve ever wanted to stand with one foot in the northern hemisphere and one in the southern, you have this opportunity during your trip to Sumatra! The imaginary line passes through Riau, West Sumatra, and various islands and villages on the way.
If you’re travelling from Medan to Padang on the Trans-Sumatran highway, you’ll pass right over the equator in a tiny village called Bonjol. There’s even a line painted on the road and an overhead sign to mark the milestone. Definitely worth getting out and taking a quick photo to mark the occasion!
Weather in Sumatra
Although Sumatra as a whole has a pretty stable climate, there are some differences between North Sumatra and South Sumatra, which are “split” by the equator.
Northern Sumatra has a slightly more tropical climate and can see rain year-round. There is a less defined difference between wet and dry season than in the southern areas.
While this doesn’t equal non-stop monsoons and awful weather for days or weeks on end, you can expect more rain in the northern regions of Sumatra, particularly in the jungle areas!
Temperatures don’t vary much throughout the year. The average is 27-28 degrees C (80-82F) year-round, with lows of 22 (71F) and highs of 31-32 (87-89 F).
However, at times during dry season, those low 30s certainly feel a lot hotter than they really are!
For some relief from hot, sticky days, head to highland areas like Berastagi and Lake Toba in the North, and Padang and Bukittingi in the South. Hiking and outdoor activities are much more bearable when it’s a few degrees cooler and the humidity isn’t quite as stifling!
Seasons in Sumatra
Sumatra has only two seasons – wet and dry; however, the difference between the two isn’t as dramatic as you might expect.
We can provide you with general data on the seasons, but there’s never any guarantee either way.
In the last few years, the weather has become less predictable – rainy seasons are short in some areas and late in others; some years the rain is torrential, and in others, there’s only a wee bit more than in dry season.
Dry Season in Sumatra
Dry season in Sumatra generally begins in February and ends around September, although it’s hard to predict with any kind of precision, and does vary for different areas.
The southern half of Sumatra has a more pronounced wet and dry season than the northern areas. April to October are the driest months.
If you’re heading to the most northernmost parts of Sumatra – like Banda Aceh – you should aim to go between June-August and February-March for the driest weather.
If Padang is your destination of choice and you want to avoid rain, visit between June and August.
Wet Season in Sumatra
In North Sumatra, the line between wet and dry season is blurred, with rain showers possible year-round; however, there tends to be more rain from October to January in the northern provinces.
The heaviest rains are usually in December/January in the north and January/February in the south.
In the far north, in Banda Aceh and Pulau Weh, the most torrential rainfall hits between September and January, and it can also be a bit soggy during April and May.
The Western regions of Sumatra tend to see a bit more rain than the rest of the island and can be particularly damp from October to December.
Rainy season also coincides with low season, so you’ll have many places to yourself if you visit in the wettest months.
Best Time to Visit Sumatra - Weather Month by Month
The year starts with most of Sumatra experiencing the final months of the wet season, which in many places, are often the wettest.
With heavy rainfall, travel off the beaten path (which, let’s face it, is most of Sumatra) can become challenging as the bad roads become more challenging to navigate.
The average high throughout the island is 31 degrees Celsius (87F), and the average low 22-23, (71-73 F) but humidity is high thanks to all the moisture around.
In the north, rainy season is easing up; however, the wetness is likely to hang around for another month or two in South Sumatra. Road travel could be an issue, depending on where you’re going.
If you’re planning to hit the surf, the waves are a bit smaller this month, which is great for beginners!
Be aware that Chinese New Year falls on February 12th in 2021. The weekend around this date is often extremely busy in popular tourist hot spots such as Lake Toba. It’s one of the few times of year you may need to book in advance for a room!
As the rainy season gradually passes, the temperatures start heating up. From March to May, Sumatra will see its highest temperatures.
Thankfully, there’s not a massive difference throughout the year, though.
The temps usually top out in the low 30s (high 80s F) – but the humidity often makes it feel hotter than it really is!
For surfers, the conditions are clean but the swell is still modest.
In theory, South Sumatra should start drying out this month. Less rain throughout the island makes the next few months the perfect time for a beach trip, and the conditions are ideal for snorkelling or diving.
This is a great month to head out to explore the beaches and jungle areas in southern Sumatra.
April often marks the beginning of surf season, particularly in Mentawai and surrounding areas.
Tourists should note that the month of Ramadan may begin in April (the dates vary from year to year.) In 2021, it starts on around April 13th and ends on May 12th.
Ramadan is a sacred month for Muslims. While travelling is still fine during this time, you may find your daily routine is impacted by the closing of shops and restaurants during the day.
May is a great time for Sumatra travel, as long as you don’t mind being a little sweaty! Although the weather is generally dry and calm, high season is still a few months off, so you can enjoy lower prices and meet fewer tourists around now.
This is an excellent time for all you outdoor adventurers; diving, surfing, hiking and trekking are prime activities during the next few months.
Ramadan continues into May, culminating in Eid al-Fitr (Hari Raya Idul Fitri) on May 13 and 14th (2021). This is a huge celebration where many Indonesians travel home (or travel elsewhere with their families) to be together. Popular tourist areas may be packed and flights more expensive.
The dry season throughout Sumatra continues for the next few months. From Pulau Weh in the north to Lampung in the south, you’ll see more sunshine and less rain.
Bear in mind that areas with a more tropical climate have a higher chance of year-round rain, especially in the jungle/rainforest areas.
June is peak surf season in Sumatra, with many pros heading to Krui and other hotspots. The temperatures are pleasant at around 27-32 Celsius (80-89 F), and the high humidity (80 percent!) makes the ocean the perfect place to be.
It’s hot, humid and dry, especially in North Sumatra. If you find it a bit much, head for the highland areas like Berastagi and Lake Toba in the north or Padang in the south to cool down a little.
Dry season is still in force throughout most of Sumatra, making jungle trekking and volcano hiking less treacherous; less rain means it’s easier to navigate throughout the jungle!
July also marks the beginning of high season. Although tourist numbers never get crazy in Sumatra, you’ll see more backpackers arriving, particularly in hotspots.
The waves are picking up this month too, with swells as high as 15 feet rolling in to popular surf areas.
The average temperature is 28 degrees Celisus (82F), and humidity is still a very sticky 80 percent.
Hello peak season! August is one of the best months to visit for all kinds of travellers.
For surfers, you might even find the massive swells a little overcrowded in the top surf spots.
This is a great time to head to highland areas to escape from the sweltering humidity. Or you can always go in search of a waterfall to refresh yourself under!
Dry season is winding down, and the humidity drops to around 70 percent – what a relief! Temperatures range from 23-30 degrees (73-86 F).
High season is also winding down as tourists head home. For those who still have time, this is a great month for heading into the jungles in search of adventure.
The slightly more tropical north usually sees the wet season return during October, around a month before it hits the southern areas.
You may start to see an increase in rainfall along the southern coasts, worsening from now until December.
Surfing is still a great option, especially as the waves are less crowded from now on.
Humidity is still up there – in the 70s – and temperatures remain between 23-33 (73-91 F).
This is the last month to get in some quality hiking before rainy season really kicks in, and a good time to score a bargain during shoulder season.
South Sumatra starts seeing increased rainfall this month. Leading into full-on wet season, island hopping and beach chilling may not be guaranteed again until next year.
The weather, at best, is unpredictable, although more rain everywhere is a given. The waves are getting bigger and wilder, too. Maybe great for surfers; not so great for those wanting to explore offshore islands by boat.
Some areas are experiencing intense tropical downpours now. In Banda Aceh, for example, December is the wettest month of the year.
If you’re planning a trip to one of the smaller islands in Sumatra, be aware that bad weather could impact boat schedules.
There’s more rain and smaller waves. Humidity is stifling at 80 percent in the lowland areas, and the average temperature is around 27 (80F).
Although wet season is still in force over most of the island, December and January can be quite busy with local holidaymakers.
Best Time for Surfing in Sumatra
The peak time to surf in Sumatra is from April to October, in dry season. This is when winds from the SSW hit the coast, producing perfect, consistent swells that are up to four metres high (6-12 feet).
In particular, June and July see consistent swell in Krui, Lampung, Mentawai, Nias, and other surf spots.
If you can’t manage to go surfing Sumatra during peak season, no worries; off-season still gets some pretty decent surf through November to March, with two-metre-high swells.
While off-season sees less consistent waves, the conditions are still good, and there are fewer crowds.
Best Time for Diving Sumatra
If you dream of snorkelling or diving in Pulau Weh, we’ve got great news! You can dive in the warm waters of the Andaman Sea year-round.
Water temperatures are between 26 degrees Celsius (78F) and 29C (84F), and the visibility is around five metres (15 feet), depending on where you are and the time of year.
However, if you’re looking for the optimal weather, plan your trip for dry season, between February and October.
Padang is dive-able year-round, although visiting during dry season means less chance of torrential rain or strong winds.
In the Bintan Island – Riau Archipelago, the currents start to get stronger from December to February, so it’s an ideal time for getting in some drift dive practice.
Best Time for Trekking in Sumatra
You can trek and hike at any time of year in Sumatra, although visiting during dry season (Feb-Sept) is a good idea if you want a good chance of avoiding torrential downpours.
Bear in mind, there are no guarantees of dry weather in the rainforest – even in dry season! Bring a raincoat regardless of when you visit.
If you’ve got your heart set on hiking a volcano or two and heading into a national park, by all means, try to come in the middle of dry season.
This also happens to be high season for tourists, so depending on where you’re headed, you might be seeing more humans during your trek than animals between June and August.
If you decide to go orangutan trekking in Sumatra during wet season, it’s not a problem. In many areas, the days are still fine and the torrential rain appears in the mid-to-late afternoon and passes through – but not always!
Things to be aware of if you are trekking in wet season (or dry, for that matter, because you never can be sure in a tropical climate!):
- Bring quick-drying shoes and clothes
- Pack a pair of non-slip shoes/boots
- More moisture means more leeches and mosquitos; bring appropriate insect repellent
- Sumatran roads can be tricky to manage at the best of times. If it’s wet, be prepared for delays, impassable areas, and a whole lot of mud.
- Stick with your guide at all times. There are plenty of gorgeous rivers in the jungle, but they can very rapidly become dangerous after rain. Do as your experienced guide tells you and don’t take any chances.
- Make sure your pack has a waterproof cover, and have a couple of dry bags on hand for your electronics and other precious items that can’t get damp.
Because many people fly into Kuala Namu Airport in Medan, North Sumatra, it’s worth mentioning the weather in this chaotic metropolis.
There’s not really a best time to visit Medan. You can expect it to be hot and super-muggy year-round. In the central city area, it’s so humid and lacking wind that it feels a lot hotter than it really is.
The average low is 22 degrees Celsius (71F), and the high is 31-32 degrees (87-89F). It’s hot and stinky!
The wettest period is from October to December, and naturally, sees the least amount of sun.
The driest months in Medan are February, March, June, and July. The wettest period lasts from August until September.
Public Holidays in Sumatra
When planning a trip to Sumatra, it’s useful to know about some of the most important public holidays celebrated in Indonesia, as these can potentially impact your travel plans.
A number of the holidays are set by various officials according to the Muslim calendar, meaning the date differs slightly from year to year.
Dates provided here are sourced from the official website and may change closer to your trip, so make sure to double-check.
No surprises here – New Year’s Day on the 1st is a public holiday throughout Indonesia. Expect local crowds in holiday areas.
Chinese New Year is always celebrated on the first day of the Chinese lunar calendar, therefore may vary from year to year.
At this time of year, Chinese families often take the opportunity to travel together.
Tourist areas like Lake Toba are often extremely busy, and you might find the price of domestic flights or international flights soars around this time.
In 2021, Chinese New Year will fall on February 12th.
March 11th (2021) marks Isra Mi’raj, a public holiday in Indonesia that recognises the Ascension of the Prophet Muhammed.
The holy month of Ramadan has different dates every year, according to the Islamic calendar.
In 2021, it is expected to begin around April 13th and last until May 12th.
While not a public holiday as such, Ramadan is an important event for Muslim Indonesians, who fast from sunrise until sunset for an entire month. Known as the month of giving, it’s a time to slow down, show self-restraint, and donate to those in need.
Because Sumatra has a sizeable Muslim population, there is likely to be some impact on your travels in Sumatra – but it does depend on where you go. Lake Toba, for instance, is a majority Christian area, so there will be little to no change to life as usual here for tourists.
In other areas, restaurants and cafes will likely be closed during the day – although tourist hotspots will still have places where foreign tourists can go and eat.
Out of respect for those fasting, any warungs that do serve food during the day may cover their doors or windows with fabric.
If you’re travelling through Sumatra during the month of Ramadan, keep this in mind and make sure to have a few snacks with you if you’re heading off the beaten path.
As the sun sets in the evenings, the fast is broken, and you’ll likely find large groups of people gathering to eat and drink in a festive atmosphere.
Good Friday is a public holiday and will be celebrated on April 2nd, 2021.
May 1st every year is a public holiday in honour of Labour Day.
The Christian holiday of the Ascension of Jesus Christ takes place on a Thursday.
In 2021, it will be recognised on May 13th.
Eid Al-Fitr (Hari Raya Idul Fitri). The holy month of Ramadan continues into early May, concluding with the three-day celebration that is Eid Al-Fitr. This period is also known simply as Lebaran.
During Idul Fitri, millions of Indonesians travel to be united with friends and family and celebrate together. It’s quite possibly the most significant public holiday in the country.
Within Sumatra, tourist areas may be crowded and hotels booked out. On top of this, flights into, out of, and around Sumatra before, during, and after these holidays may be booked out and far more expensive than usual! Traffic jams and delays are common during this time.
If you’ll be travelling to or within Sumatra during this time, we recommend booking well in advance.
The date changes annually, but in 2021, the official public holidays are expected to occur on 13th and 14th of May.
Waisak Day is an Indonesian Buddhist public holiday taking place on a different date every year. In 2021, it will be acknowledged on May 26th.
Occurring on June 1st every year, Pancasila is a public holiday observing the five principles – or Pancasila – that govern Indonesia.
Idul Adha – also known as the Day of Sacrifice – is an Islamic holiday falling on a different date every year.
In 2020, it will be recognised on July 31st. In 2021, it will be on July 20th.
Islamic New Year (Muharram) occurs on different days every year. In 2020, it will happen on August 20th and be recognised on August 21st.
In 2021, it falls on August 10th. This is a public holiday and an important celebration for Indonesian Muslims.
Independence Day. Every year on August 17th, people throughout the country celebrate Indonesian Independence Day. It’s a great chance to witness (and join in on) some of the fun activities that take place throughout Sumatra.
No holidays of note.
Prophet Muhammed’s Birthday Holiday is scheduled for 28th, 29th and 30th October in 2020. In 2021, the Islamic calendar celebrates the birth of the Prophet Muhammed on October 19th.
No holidays of note.
Christmas Day on December 25th is celebrated through much of Sumatra, although the extent will depend on which area you happen to be in during this month.
Families head to church and enjoy shared meals together.
Of course, New Year’s Eve on the 31st is a huge event with family gatherings, local parties, and copious amounts of fireworks!
What’s the Time in Sumatra?
Sumatra is seven hours ahead of GMT (general mean time) – the same time as several other countries in Southeast Asia, such as Thailand, Cambodia, Vietnam, and Laos.
Because Indonesia is so spread out, there are actually three different time zones in the country.
Sumatra, Java, and West/Central Kalimantan share the GMT+7 zone.
Bali, Nusa Tengarra, South and East Kalimantan are GMT+8, and Irian Jaya and Maluku are GMT+9/
Fires and Haze in Sumatra
Although dry season is the best time to go to Sumatra weather-wise, it does carry potential risks.
One of the most concerning – for locals, tourists, and the environment – is the haze caused by hundreds of thousands of fires burning throughout Sumatra and Borneo.
These fires are deliberately lit (often illegally) to clear land to make way for palm oil and pulpwood plantations. They burn out of control for months during dry season, causing a dangerous haze that blankets Sumatra and spreads as far as Singapore and Malaysia.
In recent years, the fires started as early as June, but the haze has peaked later in the year during September and October.
The resulting haze may impact your holiday. In 2019, we saw areas throughout the entire island of Sumatra blanketed in smog that obscured the sky for weeks, causing health issues for hundreds of thousands of people.
It’s difficult to predict if or when the haze will be a problem every year in Sumatra, but going by recent years, it will show up at some point during dry season and be worse if it’s a particularly intense year with little rain.
The haze in Sumatra dissipated in September 2019 with the arrival of rainy season.
If you dream of travelling to Sumatra but have dates that aren’t flexible, don’t stress – any time is a great time to visit this incredibly diverse island.
Wet season brings lush natural beauty, stunning, refreshing rainstorms, and just makes those waterfalls all the more impressive. Dry season provides gorgeous sunny days perfect for trekking or relaxing in a hammock. But both seasons offer a bit of everything, so hopefully, you don’t have to miss out.
Regardless of when you visit Sumatra, you’re guaranteed the adventure of a lifetime.