Weather in Indonesia in September

September is the tail end of the dry season – and one of the best times for traveling to Indonesia. Expect plenty of sun, ideal for beach days, volcano hikes, and island-hopping without the crowds. Here’s what you need to know about the weather in Indonesia in September.

Indonesia in September at a glance

• September in Indonesia marks the end of the dry season in many regions.
• Temperatures typically range from 75°F to 89°F (24°C to 32°C).
• There may be occasional showers as the country transitions to the wet season.
• The weather in September in Indonesia is still generally dry and warm, and this month is less crowded compared to peak months like July and August. 

What is the weather like in Indonesia in September?

The weather in Indonesia in September is predominantly dry and sunny, as this month is right at the end of the dry season (and the beginning of the wet season). The temperatures stay warm and are often accompanied by moderate humidity levels.

In terms of rainfall, you can expect around 50-80 mm on average in September. This amount shouldn't deter your plans too much, but it's always a good idea to pack a light rain jacket just in case.

At the onset of the wet season, the rain often comes in short, intense bursts rather than prolonged drizzles. These showers help to cool down the atmosphere temporarily and can actually lower the overall humidity levels, especially right after a rain shower.

During this month, you can still enjoy outdoor activities like temple visits, beach hopping, and hiking without worrying too much about rain. However, keep in mind that there might be some short showers towards the end of the month as the wet season starts rolling in.

Overall, September can be a great time to visit Indonesia because the (mostly) dry, sunny weather is perfect for exploring the country without breaking the bank. 

Average daily temperatures in September

Daytime temperatures typically peak around 88°F (31°C), providing hot and sunny conditions that are perfect for outdoor activities and beach outings. At night, temperatures cool down to about 75°F (24°C).

Sea temperatures remain warm, averaging around 81°F (27°C), making the waters excellent for swimming, snorkeling, and diving.

The weather in Jakarta and Java

Jakarta and Java experience warm and increasingly wet weather in September, with daytime temperatures averaging around 86°F (30°C). Humidity levels rise as the month progresses, and rainfall becomes more frequent and intense, often in the form of afternoon thunderstorms. 

The weather in Bali and the Lesser Sunda Islands

In September, Bali  and the Lesser Sunda Islands, including Lombok and Flores,  have temperatures ranging from 79°F to 86°F (26°C to 30°C). The islands experience an increase in rainfall, especially towards the end of the month, although sunny days are still common earlier on. Humidity levels rise, contributing to occasional tropical showers that refresh the landscapes and maintain the lushness that attracts tourists to Bali's beaches and cultural landmarks.

The weather in Sumatra

Sumatra in September sees temperatures between 77°F and 86°F (25°C and 30°C). Coastal areas like Medan and Palembang experience increasing rainfall, transitioning towards the wet season. Inland regions may receive more significant precipitation, sustaining the island's rich rainforests and wildlife habitats. 

The weather in Papua and eastern Indonesia

Papua and eastern Indonesia, including Sulawesi  and the Moluccas, have temperatures ranging from 81°F to 90°F (27°C to 32°C) in September. The region experiences increasing rainfall as it enters the wet season, with humidity levels rising significantly. Heavy showers are common, particularly in mountainous areas and rainforests.

Is September a good time to visit Indonesia?

September falls at the tail end of the dry season, and is an ideal time for travel. The weather in Indonesia in September is typically sunny and dry, with clear skies and minimal rainfall, especially in popular tourist areas like Bali, Jakarta, and Yogyakarta. 

Temperatures stay warm, which is perfect for beach outings and water activities. Swimming is definitely possible, and the seas are generally calm, making it a great time for snorkeling and diving in places like the Gili Islands or Komodo National Park. 

With fewer tourists compared with the peak months of July and August, September offers a more relaxed and uncrowded experience. It is also a fantastic time to explore Indonesia’s cultural traditions, from visiting ancient temples like Borobudur and Prambanan to witnessing local festivals.

On 10-day Indonesia trips, the mostly dry weather gives you enough scope to combine culture with a more active section, such as trekking Mount Bromo or Mount Rinjani, without the route feeling too tight. Pack lightweight rain gear and stay flexible with outdoor activities, especially in areas that are beginning to transition into the wet season.

What about the crowd and cost?

If you're planning a trip to Indonesia, September could be the sweet spot for you in terms of crowd and cost considerations. As the country transitions from its peak tourist season of July and August, you'll find that the crowds begin to thin out, creating a more laid-back atmosphere at popular spots, with shorter lines at attractions and more options for accommodation compared to the busier summer months.

Accommodation prices also start to ease off in September as demand subsides from the high season rush. This makes it a great time for budget-conscious travelers to explore Indonesia without breaking the bank on lodging.

For those seeking similar weather conditions but even fewer crowds, consider visiting in April, May, or October. These months offer pleasant weather comparable to September but with fewer tourists, promising a potentially more relaxed and affordable trip.

Rough Guides tip: Find even more ideas for your fall adventure with our guide to the best places to travel in September.

Festivals and events in Indonesia in September

When preparing for your journey to Indonesia, be sure to look into the various festivals and events happening across the archipelago during your stay. It's advisable to secure accommodations early as they are often in high demand. For further travel inspiration and suggestions, delve into our Indonesia trip ideas.

Lake Toba Festival

The Lake Toba Festival is an annual event held in the Lake Toba area, North Sumatra. It celebrates the natural beauty of Lake Toba, the largest volcanic lake in the world. The festival features cultural performances, traditional Batak music and dance, boat races, and exhibitions of local handicrafts and culinary delights. 

Erau Culture Festival

Erau Culture Festival is a traditional cultural festival held in Tenggarong, East Kalimantan, usually in September. It celebrates the indigenous Dayak culture, including the Kutai, Kenyah, and Bahau tribes. The festival features ritual ceremonies, traditional dance performances, ritual mask displays, and handicraft exhibitions. Erau Culture Festival highlights the Dayak people's spiritual beliefs, cultural heritage, and artistic expressions, attracting visitors from across Indonesia and beyond.

Layang-Layang (Kite Festival)

Layang-Layang is a traditional kite festival held in various locations across Indonesia, particularly in Bali and Sumatra. It celebrates the windy season and includes kite-making workshops, kite-flying competitions, and colorful kite displays featuring intricate designs and sizes. 

Taman Ujung Festival

Taman Ujung Festival is a cultural event held at Taman Ujung Water Palace in Karangasem, East Bali. The festival celebrates the historic water palace built by the royal family of Karangasem and includes cultural performances, traditional music, dance showcases, and exhibitions of local arts and crafts

Balinale – Bali International Film Festival

Balinale is an annual international film festival held in Bali, usually in September. It showcases a diverse selection of Indonesian and international films, including feature films, documentaries, short films, and animations. Balinale aims to promote cultural exchange and collaboration within the global film industry. The festival includes film screenings, workshops, panel discussions, and networking events.

Krakatau Festival

Krakatau Festival is an annual event held in Lampung, Sumatra, usually in September. It commemorates the eruption of Krakatoa in 1883 and celebrates the natural beauty and ecological significance of the Krakatoa Islands. The festival includes cultural performances, exhibitions, seminars on volcanic studies, and eco-tourism activities such as hiking and snorkeling. Krakatau Festival aims to raise awareness about volcanic conservation and sustainable tourism in the region.

Festival Lembah Baliem

Festival Lembah Baliem is a cultural festival held in Wamena, Papua, usually in September. It celebrates the indigenous tribes of the Baliem Valley, including the Dani, Lani, and Yali tribes. The festival features traditional dances, mock tribal wars, pig races, and exhibitions of tribal arts and crafts. 

Plan your trip with our Indonesia itineraries

Our Indonesia itineraries are crafted to help you experience the best of the country, stress-free. Think of them as a starting point — perfect for planning, but flexible enough to adjust to your own pace and interests. After all, travel is about freedom, but a little planning goes a long way.