Indonesia needs more than one calendar
Indonesian tourism guidance describes April–October as a broad dry season for much of the country, including Bali, while highlighting regional variation. Raja Ampat guidance instead points to October–April as a useful marine-travel planning period. These differences are why a single green bar for Indonesia can mislead.
Singapore is a different case
Singapore has rain throughout the year, with changing monsoon and inter-monsoon patterns. An island visit can be considered in many months, but daily forecasts, storms and visitor notices matter more than a promise of a dry day.
Use Philippine guidance locally
PAGASA describes a broad dry season from December to May and also identifies distinct climate patterns within the country. Treat a national summary as a starting point for local research, not as permission to ignore conditions around a specific sailing.
Match the activity
A period that suits a coastal hotel stay may not suit an exposed crossing or a particular dive site. Ask about the route and activity separately. A month label cannot determine sea state, visibility or access on your date.
Keep a workable alternative
Leave flexibility around weather-dependent travel and avoid a tightly timed flight immediately after an essential ferry connection. Use the calendar to narrow choices, then confirm the detailed plan through current local information.
Sources & further reading
Official sources support the factual background. Comparisons, route outlines and budgeting methods are editorial suggestions. Check changing details before travelling.