Indonesia has a tropical climate with an average constant temperature of 30°C. The equator runs right through the country (Sumatra). There is not always a clear blue sky but the temperature remains pleasant. In higher or mountainous areas it is cooler once the sun has set. On the tops of volcanoes it is usually icy cold.
Indonesia is also good to travel in the monsoon (the rainy season); the humidity is higher, but that also has advantages; less dusty and there are more fruits. In the monsoon season, it rains more often, that is obvious. However, it does not rain continuously. When it rains, it is usually in the afternoon or evening/night and then briefly very heavily, so that the drains cannot handle it and small rivers form on the streets. As soon as the rain stops, everything resolves itself very quickly.
The rainy season on most islands follows a cyclical pattern. It starts with an occasional shower, then there is a peak period with a heavy shower every day, in the peak months it rains for a few hours, then it decreases again with an occasional (heavy) shower.
An indication (even in Indonesia the weather cannot be predicted for the long term) of the monsoon:
- Sumatra: October (sometimes earlier) to March
- Java: November to March with the peak in January and February
- Bali: December to March with the peak in January and February
- South Sulawesi and Central Sulawesi (Torajaland): December to February
- North Sulawesi (Manado): May to July
- Lesser Sunda Islands: May and June (southern coasts), December to March (northern coasts)
- Kalimantan: November to February
- Moluccas: June to September