When is the best time to visit Indonesia?
For a first trip combining Bali, Java and Komodo, May to September is usually the best time to go: Java and Bali are drier, and Komodo is generally better suited to boat days. Raja Ampat is different, with October to April usually bringing calmer seas. Indonesia is too large for one national “best month”, so the right dates depend on which islands matter most.
Full answer
Indonesia is too large for one weather calendar, but Bali, Java and Komodo generally favour the middle of the year. Bali and Java are usually drier from April to October, and Komodo tends to be better for boat and beach days during the drier months. If those places make up your first trip, May to September is the safest broad choice.
Raja Ampat is the big exception. Its better boating and diving months usually fall from October to April, when seas are calmer; May to September is typically windier and rougher.
The wetter months do not make Bali or Java impossible, and seasons vary from year to year. Recheck conditions before a boat-heavy, diving or hiking trip. For most travellers, though, the useful distinction is simple: May–September for Bali, Java and Komodo; October–April for Raja Ampat.