January is in the rainy season for much of Indonesia, which comes in the form of short sharp downpours, usually late in the afternoon. In between rainfall, bright blue skies and sunshine can normally be expected.

In January, some rain, usually in the form of an afternoon shower can be expected in Bali and Lombok and much of Indonesia on 2 out of every 3 days. This is the rainiest time of year in much of Indonesia.

In Bali and Lombok 320 mm of rain can be expected in January, which is about 10 times the amount of the driest month (September). Temperatures still average around 30 degrees and 7 hours of sunny clear skies are average for this time of year.

In Sumatra, the monsoon can make some roads impassable during this time of year, so some planning is required.

In Jakarta 4 hours of sunshine daily is average for January with almost 400 mm of rainfall. Jakarta can often be flooded at this time of year. Yogyakarta has similarly high rainfall at this time of year.