Is the Singapore Strait rough? What to expect on the crossing
Rarely. The Singapore Strait is a semi-enclosed channel, and a study of five years of wave data finds an average significant wave height of 0.275 m. The exceptions are northeast monsoon surges in January and February and early-morning squalls in the southwest monsoon.
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Strait · South-east Asia · Reputation among passengers: mixed: commonly reported as uncomfortable in the wrong conditions.
- Low
- Moderate
- High
- Very high
Roughness summarises typical reported conditions for this crossing, not a forecast for any given sailing.
Sheltered strait, monsoon wind chop
In the Nausea Index table of the 121 sea crossings we cover, the Singapore Strait is rated manageable, one of 81 in that band, with 40 rated higher. Full table: the roughest sea crossings, ranked.
Key facts
- The Singapore Strait is a strait, and passenger reports place it in the moderate roughness band.
- The mechanism behind that reputation: Sheltered strait, monsoon wind chop.
- Conditions are reported roughest in January, February and December.
- The calmest months are usually April, May and October.
- It is also known as Selat Singapura.
Why does the Singapore Strait get rough?
Shelter. The strait is a 113 km channel, 19 km wide, with Singapore to the north and the Riau Islands to the south, so wind has little distance to build waves. ERA5 wave data for 2021 to 2025 gives a mean significant wave height of 0.275 m and a maximum of 1.165 m. Tidal streams are strong, and in the northeast monsoon a monsoon current of 1 to 1.5 knots flows west through the strait.
When is the Singapore Strait roughest?
The northeast monsoon, December to early March, is the rougher season, with the highest median waves in January and February. April, May and October are the calmest months. June to September sits in between, with a secondary peak in July and occasional Sumatra squalls with gusts of 40 to 80 km/h between the predawn hours and midday.
| Roughest water in Jan | Roughest water in Feb | Roughest water in Mar | Roughest water in Apr | Roughest water in May | Roughest water in Jun | Roughest water in Jul | Roughest water in Aug | Roughest water in Sep | Roughest water in Oct | Roughest water in Nov | Roughest water in Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Rough | Rough | Mixed | Calm | Calm | Mixed | Mixed | Mixed | Mixed | Calm | Mixed | Rough |
Typical seasonal pattern, not a forecast. Any month can deliver a calm crossing or a bad one. Check the marine forecast for your sailing date. Select a month to see every sea and ferry crossing ranked for it.
Where to be on board
Front to back
- Bow (front)Avoid
- MidshipBest
- Stern (aft)OK
The crossing: 45 minutes to 1h10
Roughest stretch: The open eastern leg toward Bintan, once clear of Changi
Sit low and near the middle. Most sailings last about an hour, so any chop is short.
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The crossings that cross it
| Route | Typical duration | What to know |
|---|---|---|
| Tanah Merah to Bandar Bentan Telani (Bintan) | about 1 hour 10 minutes | Bintan Resort Ferries, from Tanah Merah in eastern Singapore. |
| HarbourFront to Sekupang (Batam) | about 45 minutes | Batam Fast quotes about 45 minutes of sailing. |
| HarbourFront to Batam Centre | about 45 to 70 minutes | Batam Fast gives 45 to 70 minutes of sailing for its Batam routes. |
What helps on this crossing
- If you can pick the month, avoid January and February. They have the highest median waves, and the monsoon surges that push waves past 1.0 m come then.
- Check the Meteorological Service Singapore marine pages before you go. They list significant wave, wind wave, swell and surface wind forecasts. In June to September, look for squalls too: they come between the predawn hours and midday.
- Runs to Batam take 45 to 70 minutes by the operator's own figure, so any chop is short. Keep your eyes on the horizon through it and put your phone away.
For the full toolkit see the seasickness guide, or what to do once it has already started. For what the trials actually say about the oldest trick on that list, see the verdict on looking at the horizon. If the rocking follows you ashore afterwards, that is land sickness, which is normal, and it passes.
Frequently asked questions
Is the Singapore Strait rough in January?
January and February are the roughest months. A study of the strait finds median waves of about 0.40 m, with outliers above 1.0 m during northeast monsoon surges. That is small beside an open sea, but the model smooths local peaks. The same study notes waves of about three metres in January 2025, well above its 1.165 m maximum.
Is the Singapore Strait rough in July?
A little. July is the secondary wave peak of the year, in the mature phase of the southwest monsoon. June to September runs at about 0.20 to 0.28 m. Squalls with gusts of 40 to 80 km/h can arrive between the predawn hours and midday.
Which month is calmest for the ferry to Batam or Bintan?
April, May and October. Those inter-monsoon months have the lowest median wave height in the study, about 0.18 m, with little spread. Meteorological Service Singapore describes winds in April, May, October and November as light and variable.
Is the Singapore to Batam ferry rough?
Usually not. Batam Fast gives 45 to 70 minutes of sailing, and the strait is semi-enclosed, so wind has little distance to build waves. The roughest runs fall in the northeast monsoon, December to early March.
Other crossings
Sources & further reading
- https://en.wikipedia.org/wiki/Singapore_Strait
- https://www.weather.gov.sg/climate-climate-of-singapore/
- https://journal.unhas.ac.id/index.php/jmsk/article/download/51084/15000/183558
- https://www.tidetechmarinedata.com/news/the-complex-currents-in-singapore-strait
- https://www.brf.com.sg/
- https://www.batamfast.com/destinationguide/sekupang.ashx
- https://www.batamfast.com/destinationguide/batamcenter.ashx
- https://id.wikipedia.org/wiki/Selat_Singapura
Sea conditions described here are typical patterns drawn from published marine and operator information as of July 2026, not a forecast: conditions on any given sailing depend on the weather that day, and any month can deliver a calm crossing or a bad one. Route and operator names are trademarks of their respective owners; Dizzout is not affiliated with or endorsed by them. Seasickness sensitivity varies from person to person; this page is informational and not medical advice.