Is the Gulf of Saint-Malo rough? What to expect on the crossing
Sometimes, mostly from November to March. The gulf has huge tides and plenty of rocks and reefs, and the Charting Progress 2 report on UK waves finds a high risk of large waves between October and March. The short hops between Jersey, Guernsey and Saint-Malo take 1 to 2 hours.
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Gulf · Between Brittany, Normandy and the Channel Islands · 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.
Huge tides and island reefs in the western Channel
In the Nausea Index table of the 121 sea crossings we cover, the Gulf of Saint-Malo is rated manageable, one of 81 in that band, with 40 rated higher. Full table: the roughest sea crossings, ranked.
Key facts
- The Gulf of Saint-Malo is a gulf, and passenger reports place it in the moderate roughness band.
- The mechanism behind that reputation: Huge tides and island reefs in the western Channel.
- Conditions are reported roughest in February and December.
- The calmest months are usually April, May, June, July, August and September.
- It is also known as Golfe de Saint-Malo (French) / Pleg-mor Sant-Maloù (Breton).
Why does the Gulf of Saint-Malo get rough?
The Gulf of Saint-Malo is the south-western part of the English Channel, between Brittany, Normandy and the Channel Islands. The tides here are among the biggest in Europe: Mont-Saint-Michel Bay reaches up to 16 m on the highest tides, and Guernsey waters combine a tidal range of 10 m with currents of up to 12 knots. There are also many islets, rocks and reefs, and Condor schedules its sailings around tidal restrictions in its ports. The Charting Progress 2 report on UK waves finds a high risk of large waves from October to March.
When is the Gulf of Saint-Malo roughest?
The Charting Progress 2 report on UK waves puts the peak around January, with a high risk of large waves from October to March. Wave reanalysis data (ERA5) ranks February and December highest in the western gulf and June and July lowest. Condor says weather can also change its sailing durations.
| 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 | Roughest | Rough | Calm | Calm | Calm | Calm | Calm | Calm | Mixed | Rough | Roughest |
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: 1 to 12 hours
Roughest stretch: The open Channel leg before the island shelter
Stay low and near the middle of the ship, face forward and keep your eyes on the horizon.
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The crossings that cross it
| Route | Typical duration | What to know |
|---|---|---|
| Poole to Guernsey | About 3 hours | Condor Voyager fast ferry. Condor calls it a peak-season service and lists it on Friday to Monday, so check the current timetable. Weather can also change the sailing time. |
| Jersey to Guernsey | About 1 hour by fast ferry, 2 hours by conventional ferry | Condor Voyager takes about 1 hour and Commodore Clipper about 2 hours. |
| Guernsey to Saint-Malo | About 2 hours | Condor Voyager, direct. |
| Portsmouth to Saint-Malo | About 10 to 12 hours | Brittany Ferries overnight sailings. |
What helps on this crossing
- Take a short hop if you can. Jersey to Guernsey takes about 1 hour on Condor Voyager and Guernsey to Saint-Malo about 2 hours, against 3 hours from Poole to Guernsey and 10 to 12 hours overnight from Portsmouth to Saint-Malo.
- Choose June to August. Wave reanalysis data puts June and July as the calmest months and December and February as the roughest.
- Sit low near the middle, face forward and watch the horizon. On the overnight Portsmouth to Saint-Malo sailing, use your cabin for the open Channel hours.
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 Gulf of Saint-Malo rough in July?
July is among the calmest months in the wave data for the western gulf. The Charting Progress 2 report on UK waves puts the high risk of large waves between October and March. Condor notes that weather can still change sailing times, so check on the day.
Is the Gulf of Saint-Malo rough in January?
January is a high month. The Charting Progress 2 report says mean wave heights in UK waters peak around January, and wave data rates February as the roughest month in the western gulf.
Why are the tides so big in the Gulf of Saint-Malo?
Mont-Saint-Michel Bay has some of the biggest tides in Europe, up to 16 m on the highest tides, partly because the bay is shallow and the Cotentin peninsula acts as a barrier. Guernsey waters have a tidal range of 10 m.
How long is the ferry from Poole to Guernsey?
Condor lists around 3 hours on the Poole to Guernsey fast ferry. It calls this a peak-season service, listed on Friday to Monday, and says weather may also change the sailing duration.
Other crossings
Sources & further reading
- https://en.wikipedia.org/wiki/Gulf_of_Saint-Malo
- https://en.wikipedia.org/wiki/Guernsey
- https://en.wikipedia.org/wiki/Mont-Saint-Michel_Bay
- https://nora.nerc.ac.uk/id/eprint/10533/
- https://nora.nerc.ac.uk/id/eprint/10533/1/WavesNORA.pdf
- https://www.condorferries.co.uk/ferry-routes-ports/ferries-to-guernsey/ferries-to-guernsey-from-poole
- https://www.condorferries.co.uk/ferry-routes-ports/ferries-to-guernsey/jersey-to-guernsey-ferry
- https://www.condorferries.co.uk/ferry-routes-ports/ferries-to-st-malo/ferries-to-st-malo-from-guernsey
- https://www.brittany-ferries.co.uk/ferry-routes/ferries-france/portsmouth-st-malo/onboard
- https://open-meteo.com/en/docs/marine-weather-api
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.