Can you visit Sumbawa by boat during the rainy season?

By Sumbawa Liveaboard Editorial Desk

Yes, you can visit Sumbawa during the rainy season, but a long liveaboard crossing is hard to find. The rains run from December to March, and one operator says crossings rarely happen then because of swell on the north coast. Whale sharks are still recorded, and one local operator says the waterfalls fill afterwards, so choose a flexible plan with spare days.

How wet is December to March?

Wet enough to shape your days. Climates to Travel marks December to March as the rainy season and gives about 1,400 mm of annual rain at Sumbawa Besar. Its rain-day count peaks in January at an average of 22. That number tells you how many days see rain, and it does not say how long the rain lasts or when in the day it falls.

Those are records from one town on land. On the water, the ISRA factsheet on Saleh Bay describes the December to February northwest monsoon in the bay as wet but light on wind. A wet morning in a sheltered bay and a swell on an exposed coast are different problems, and the next section separates them.

Under water, expect shorter visibility. Komodo Resort's monthly table gives visibility of 10 to 15 m in January and December, the low end of its year. For the full month-by-month view, see our guide to the best time for a Sumbawa liveaboard.

Do boats still run?

Rarely on the long routes. Neptune's scuba site uses that word for crossings between December and March, and gives the reason as northwest monsoon swell on the north coast. Rarely is not never, and it applies to the crossing itself, so ask about the specific boat. La Galigo and Liveaboard Indonesia start their peak or best season in April, which fits Neptune's statement.

One possible reading, which no source states: ISRA describes wind in the bay and Neptune describes swell on the open coast. Either way, a captain's judgement on the day carries much of the weight.

Whichever month you sail in, expect changes. Coralia warns that its sample itinerary may change. Tropical Snorkeling says the order of stops on its long Bali to Labuan Bajo trip depends on conditions. Those statements are general and not limited to the wet months, but they matter most in them, and you should read them as part of the product you are buying.

Are whale sharks still there?

The records say yes. The ISRA factsheet describes observations year-round from 2017 to 2022, and March, a rainy-season month, is one of the two months with the most observations. Liveaboard Indonesia also says sightings happen every month. Komodo Resort names a later season, a disagreement the timing guide sets out, so do not read this as a promise for your dates.

The harder part in these months is getting there comfortably, because the sharks' presence does not depend on the crossing. A shore-based outing avoids the long passage altogether. Our comparison of a liveaboard and a day trip sets out what that trade looks like. Check how the operator treats a morning cancelled for weather before you pay anything, because terms vary.

What is better after the rains?

Waterfalls, chiefly. The Langkah, a local operator, says the falls at Mata Jitu on Moyo flow strongest at the end of the rainy season, April to May. That is slightly later than the rainy season in the climate record, which ends in March, and the difference is useful. If that operator is right, you do not need to sail through the wettest weeks to see the falls at their fullest. Our guide to Mata Jitu from a liveaboard explains how guests reach it.

April also opens what La Galigo and Liveaboard Indonesia call the peak or best season, and it falls inside The Langkah's waterfall window. A guest who can move a December or January plan to April sails outside the months Neptune calls rare for crossings. A guest who cannot move it should shrink the plan to fit the season, not expect the season to fit a long crossing.

What should you plan for?

Plan for changes, and put the terms in writing. A short list for December to March:

• Spare days. Keep at least a spare day before any onward flight, so a late boat or a rough transfer does not cost you a connection.
• A written change policy. Ask what happens if the operator cancels or reorders stops, and what is refunded. Hold an offer from us to the same standard.
• A fallback for each stop. Ask what replaces a missed island or a missed morning at the platforms.
• Dry storage. Bring dry bags for electronics and documents, and ask where they can be kept on board.
• Lower expectations for visibility. If underwater photography is the main goal, these are not the months to pick.
• Insurance wording. Read how your policy treats weather disruption and activities at sea before you travel.

Rain also changes what is worth doing on land. Wet trails and rough transfers make long days ashore less attractive, so favour plans with short walks and flexible timing, and leave room to change your mind on the morning itself.

What other questions do travellers have about the wet months?

Is December a bad time to take a long crossing past Sumbawa?

Yes, on Neptune's account: its scuba site calls crossings rare between December and March and blames north-coast swell. Ask a specific operator if you have fixed dates, and expect few options.

Does it rain every day in January?

No, but it rains on most days. Climates to Travel gives an average of 22 rain days in January at Sumbawa Besar. The figure does not show how long the rain lasts, so plan for wet spells.

Can I still see whale sharks in the rainy season?

Yes, the records say sharks are present, though no one can promise a sighting. The ISRA factsheet describes observations year-round, and Liveaboard Indonesia says sightings happen in every month of the year.

When do Moyo's waterfalls look fullest?

April to May, according to The Langkah, a local operator, which says the falls at Mata Jitu run strongest at the end of the rainy season. That timing also falls inside what La Galigo and Liveaboard Indonesia call the peak or best season.

Will my itinerary change in bad weather?

It may. Coralia warns that its itinerary may change, and Tropical Snorkeling says its order of stops depends on conditions. Ask your own operator what it does when a stop is dropped, and get the answer in writing.

Which sources support this page?

• Climates to Travel, Sumbawa climate guide
• ISRA factsheet on Saleh Bay (IUCN SSC Shark Specialist Group)
• Komodo Resort, Sumbawa liveaboard page
• Neptune's scuba site, Sumbawa liveaboard page
• Coralia Liveaboard, sample Komodo and Sumbawa itinerary (PDF)
• Tropical Snorkeling, West Komodo and Sumbawa trip
• Liveaboard Indonesia, Sumbawa destination guide
• The Langkah, Moyo Island guide (local operator)
• La Galigo: Sumbawa liveaboard cost guide

How do I reach the desk?

Fixed on December to March? Message the desk with your month and route at +62 811-3941-4563 on WhatsApp, or write to bd@juaraholding.com, and ask what the sources say for that window. Only a boat's own operator can confirm its sailing, and nothing here is a departure offer.