Crossing Biscay - A Weatherman's Perspective

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Advice on how to tackle Biscay based on much experience of the much feared bay.

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Introduction - Why is Biscay so feared?

Biscay is feared by many yachtsmen due to its legendary reputation. To a large extent this is a result of ships, in the days of square riggers, being unable to make way to windward having been driven into the Bay by the prevailing westerlies. In addition, the Atlantic swell can build up rapidly near the coast and a number of ports can become dangerous to enter or even inaccessible.

Modern yachts, with their much more efficient rigs and their engines, should not have the same problems - particularly if they use weather forecasts carefully. Nevertheless, there have been numerous occasions over the years of yachts getting into difficulties, sometimes with fatal consequences. From the accounts that I have read, I believe that most of these problems were avoidable and that few were entirely a result of bad luck or even poor forecasts.

While we were waiting to cross Biscay in late May 2000, two yachts arrived at Audierne having been caught in winds up to at least Force 9 or 10. One had left Finisterre with no forecast "it was a nice day with a southerly wind, so we left." The other left La Coruña with only the BBC 24-hour shipping forecast and no longer term outlook. Both were disasters that nearly happened.

In bad weather, Biscay can be as unpleasant as any stretch of sea anywhere. But, if you want to get to warmer climes, as we did, and having a draft of 2 metres, then crossing it becomes a must. Having had several years sailing in and around Biscay, having talked to others and being a (now long retired) weatherman, I will try to give some help to those wishing to follow in our wake but who may have been put off by its reputation.

The Traditional Route

The "traditional" route for sailing vessels is to depart the Channel, going west of Ushant and out to or a little further than 10º W. The object is either to pass all of Spain and Portugal heading for the Canaries, to round Cape St Vincent en route for the Mediterranean or to choose a landfall on the west coast of Iberia depending upon the conditions at the time.

There are several advantages to this tactic.

  • First, by keeping far out a yacht will not be prone to the effects of steepening of the Atlantic swell in the Bay – the Continental Shelf effect.
  • Secondly, there are often increases of wind around the Atlantic coasts of Spain, notably off the extreme NW tip, Cabos Ortegal and Bares, and off Cabo Finisterre. How often does the shipping forecast say "........locally gale 8 near Cape Finisterre"? These effects can be avoided by being far enough out to sea.
  • Thirdly, you can choose your time to approach the coast whether this be La Coruña, or further south, if going to the Mediterranean or the Canaries for an Atlantic crossing.

Weather is the most important consideration for most sea or ocean passages and Biscay is no exception. For a passage to La Coruña or Bayona, - the landfall for Rally Portugal, passage times from South coast harbours should now be within the range of reasonably accurate weather prediction. Improvements in meteorology over the past 30 – 40 years made possible by the use of powerful computers have resulted in forecasts for 6 or 7 days being of sufficient quality to be produced operationally.

This requires assessing the reliability of forecasts. This is best achieved by comparing forecasts on consecutive days. If the 8-day, 7-day and 6-day forecasts for the same verifying time are similar then the forecast models are probably on the right lines.

The best time of year for this crossing is June or July. During these months, F 9 is extremely rare in the Biscay sea area. But, even then, a skipper would be well advised to be prepared for gale force winds even though none was forecast at the time of departure. At the very least, gales, even severe gale F 9s, are always possible near the Spanish coast in the Summer as the Spanish heat low deepens during the day, especially when the Azores high intensifies or moves a little to the east. During the rest of the year, winds of force 9, 10 or more would always be a possibility. A long hard look at the extended range forecasts and continuous monitoring of forecasts are essential.

In any event, and whatever the time of year, if you choose this option you must study the weather forecasts carefully - more of this later. Only go when there seems to be a good weather slot for the next 5 or 6 days. If you feel the need for further advice, especially beyond 5 days or regarding confidence levels, then discuss the prospects with the Met Office “ Speak to a Forecaster” service or one of the private weather consultants. The cost could be money well spent.

Returning to the UK, all the same considerations apply - no one wants to risk closing the SW of England in a force 9.

Clearly, this is not a venture to be undertaken lightly and many find the prospect daunting. The ever present possibility of strong winds make this passage far from ideal for many family or lightly crewed cruising yachts.

I suggest that the "outside" route should not be undertaken unless both boat and crew are equipped, and prepared, to full blue water standards.

Round the Coast

For the less adventurous, there are several options. The extreme opposite of the direct passage would be to hop around the coast in short, day passages mainly 12 hours at most. If you want an excuse for taking such a course of action then there is much to be enjoyed on the north and west coasts of Spain and France, particularly the rightly renowned Spanish Rias. For anyone with the time to spare this is well worth considering. There are, of course, some problems.

First, there are a number of ports on the west coast of France and Northern Spain that are difficult or impossible to enter if there is a big swell running. There have been instances in recent years, and several fatalities, through skippers not appreciating the effects of a big swell on the entrances to several ports from St Gilles southwards and some ports on the north coast of Spain. When approaching Royan from the north and having to use la Grande Passe to enter the Gironde there can be dangerous conditions if on a spring ebb with even a moderate Atlantic swell.

Météo France forecasts broadcast by CROSS (French Coastguard) include swell given in metres. Hopefully, you will hear, “’’’Houle non signatif’’’.”

Do not let these warnings deter you; just be careful. Listen to CROSS VHF broadcasts - they give warnings when small vessels should not attempt an entry of the Gironde. If in doubt, speak to them on VHF or by telephone to clarify a message that you have not understood fully. They are always very pleased to help and would rather do so than have to mount a rescue operation. The Passe du Sud never seems less formidable. Although the buoys are unlit; the St Nicholas lighthouse, one of the leading lights, has a good intense sector.

Entering the Bassin d'Arcachon, likewise, can be stressful, and dangerous at less than half tide. Telephone the Cap Ferret semaphore station (they speak good English if your French is too basic) and they will give you a window of entry based on the latest forecast. I usually check before leaving Royan and, again, by VHF when about an hour away from the entrance. I found them very helpful. Similarly, when leaving the Bassin; they do want to know about small craft movements.

Traversing the Spanish North Coast requires the same level of care. Some ports can be difficult or dangerous in a big swell; others less so. Read pilots and almanacs carefully and exercise the same care as for entering, say Salcombe.

Betwixt and Between

Between the two extremes of crossing direct and coast hopping, there are various options involving passages up to three days or so. Such passages should be possible for many husband and wife crews, even if they have only ventured across Channel before. Weather prediction is such that, with care, these passages can be made with considerable confidence.

My own preferred tactic, going south, is to cross the Channel to Audierne or Camaret. These give a better chance of having a favourable wind than going much further south. Audierne has my vote since it is the closest port in France to both Gijón and La Coruña. It is also south of the Raz and Chaussée de Sein - one less factor to take into account before setting off. It is well worth going up the river where you find a small marina in the heart of a delightful Breton town with all necessities (patisseries, poissoneries, boucheries, légumeries, creperies) right around the harbour.

I usually find some excuse to stay a little longer than I really need. The harbourmaster tries very hard (and succeeds) to help in any way possible. From Audierne, there are three options -

  • First, Island Hops down to any of the islands from Groix to d'Oléron and thence to Santander or Bilbao.
  • Secondly, direct to Gijón.
  • Thirdly,. direct to la Coruña.

After each it is then a case of coast hopping passages as lengthy as you feel necessary and desirable.

Island hopping

In the first case, going down the islands, departures to a Spanish port can be chosen to give a crossing time from Isle d'Oléron, Isle de Ré or Isle d'Yeu of 36 hours or less, well within the realm of sufficiently accurate prediction. Bilbao and Santander are easy entrances in most conditions.

One problem is that, with any swell running, the next all weather port after Santander, going westwards, is Gijón. This can give a longish sail along the coast. In good weather there are, of course, other viable, and attractive, options such as Ribadesella.

To Gijón

Secondly, the crossing Audierne to Gijón is likely to be up to 48 hours or so, again well within the range of usefully accurate prediction. Gijón is usually easy to enter in all but extreme conditions. In a big sea, the approach to the marina may not be too easy. In such cases, there are two options. First is the new marina in the commercial part of the harbour. Secondly, there is the apparently unprepossessing commercial port of Aviles, just west of Capo Peñas. We have entered in a 3 metre swell – call Port Control on Ch 12 first. Upriver is a yacht club marina with water and electricity and good provisioning. It is cheap! It is also nearer the airport than Gijón if you want a For a crew change.

The ultimate bolt hole is probably Viveiro, excellent in virtually all weathers with its big wall giving ample room to drop sails and prepare to enter the marina. It may be windy running into the Ria but you will be safe at the end.

From Gijón, passages around the coast present no serious problems and it is possible to visit all the Ria Altas before getting to .la Coruña. Ria Cedeira is particularly pleasant and well sheltered.

The principal hazard is probably the rounding of Cabos Bares and Ortegal at the extreme NW of Spain. Winds can often be strong here but MRCC Gijón broadcasts sea area forecasts in English and inshore waters forecasts in Spanish (as at June 2011). See my Forecast tects on the Internet pages.

Before rounding the capes it is worthwhile checking with the forecast and waiting for a good slot. Call them up on VHF, they will speak enough English to give you advice.

To la Coruña

Audierne direct to la Coruña may be up to or a little over three days. Although within the scope of reasonably accurate forecasts it pays, as ever, to listen to each and every forecast from all sources available before and during the passage. If there is any indication that the forecast is becoming more pessimistic in tone, then consider diverting to Gijón or one of the northern Rias such as Viveiro or Barquero.

After la Coruña, it is a reasonably easy day sail to Caramiñas just north of Cabo Finisterre, or a longer one to Ria Muros south of the dreaded Cape. We have rounded Finisterre three times southwards, once under boomed out Genoa and once under Spinnaker. After our three northward roundings, it was convenient to wait a few days in Caramiñas for a passage to la Coruña.

Lace making used to be a great attraction but less so adays in this fascinating little town. It is very much a port of passage and a place to meet interesting people. Almost invariably you will find someone who has been up and down the west coast of Iberia and further. Plenty of brains to be picked.

If wanting to cross to Gijón or la Coruña direct from South Coast ports from Falmouth westwards then passage times will be a day or so longer. It can make sense to go through the Chenal du Four and, perhaps, the Raz so that, if the forecast takes a turn for the worse, a diversion to Camaret or Audierne becomes feasible. You also avoid the shipping going outside Ushant.

Going northwards, all the same ideas apply and the same crossings can be used.

Which Weather Forecasts?

Wherever you sail, it is only prudent to use the local GMDSS forecasts for sea areas in Metarea II. For passages of over a day, extended range forecasts are essential both for the immediate passage and planning ahead. Forecast Synoptic charts provide a good overview of weather likely over the next 5 days - if you are happy to work with them. UK Met Office charts have the benefit of human input and the days 4 and 5 are a "consensus" of several sources of forecasts available to the Met Office. On the Internet, they are available at no cost, apart from connection and ISP charges. For longer looks ahead, try the ECMWF charts.

GRIB coded forecasts can be obtained free of charge from a number of sources. Most flexible and most cost effective is by email from. Saildocs and MailASail.

Using a Laptop, XyGrib provides a very comprehensive service including swell predictions.


Using a web browser, Passageweather gives the same information, Forecasts can be saved as a .zip file.

The development of apps for Tablets provides a convenient way of getting the same information. Several apps of varying degrees of complexity are listed on my GRIB apps page.

Although there is little to choose, iGrib is probably the easiest to use and will meet the needs of many although it does not give swell forecasts. WeatherTrack is the most comprehensive and also provides synoptic charts.

All these services use the same forecast, the US NOAA GFS (Global Forecast system.) There will be no difference in quality of forecast, only in ease of use and presentation. Most will provide forecasts to 8 days and give pretty good advice as far as 6 or 7 days ahead.

Do not waste time and money in paying for more detailed forecasts. Small weather details have short lifetimes. The GFS will not be consistently beaten by any other GRIB service currently available.


RadioFax and Radio Teletype

Offenbach and Northwood broadcast forecasts of sea state 2 days ahead, twice a day. There are forecasts of isobars and fronts out to 4 days ahead once a day from Offenbach, the DWD (German Met Service) Central Office. More usefully, the Royal Navy (Northwood) broadcasts UK Met Office charts, twice a day, up to 5 days ahead with isobars and winds.

The wind vectors (usually only shown or speeds >25 knots) show the wind direction along an arrow shaft with "feathers" indicating speed. One long feather = 10 kn, one short feather = 5 kn, a solid triangle = 50 kn.

Offenbach and Northwood broadcast forecasts of sea state 2 days ahead, twice a day.

A useful service is on Radio Teletype from the DWD. Software that can be used with the SSB Radio Fax transmissions usually contains coding to deal with RTTY as well. The Morer Weather Infobox provides the same text data.

There is an on-line version of the DWD 3-day forecasts for the route English Channel to Gibraltar is very broad brush but does give a genuinely interment “opinion.”

The example below is as received on the RTTY broadcast on the morning of Thursday, 31 May, 2001. On the basis of this information, I would not be planning to start a crossing likely to go beyond noon of Tuesday, I would, of course, be watching the next broadcast with care.

ENGLISH-CH.-W (49.6N 4.1W) SST: 13 C

FR 01. 00Z: NW-N 4-5 / 1.5 M //
FR 01. 12Z: W 3 / 1 M // //
SA 02. 00Z: NW 4-5 / 1 M //
SA 02. 12Z: NW 5 / 1.5 M //
SU 03. 00Z: N 4 / 1 M //
SU 03. 12Z: NW-N 0-2 / 1 M //
MO 04. 00Z: N 0-2 / 0.5 M //
MO 04. 12Z: S 0-2 / 0.5 M //
TU 05. 00Z: E-SE 3-4 / 0.5 M //
TU 05. 12Z: SW-W 4 / 0.5 M //
(:cell width="50

BAY OF BISCAY (46.4N 5.7W) SST: 16 C
FR 01. 12Z: NE 3-4 / 1 M //
SA 02. 00Z: NW-N 4 / 1 M //
SA 02 12Z: NW 4 / 1 M //
SU 03. 00Z: N 4 / 1 M //
SU 03. 12Z: E 4 / 1.5 M //
MO 04. 00Z: E 4-5 / 0.5 M //
MO 04. 12Z: E-SE 5 / 1.5 M //
TU 05. 00Z: SW 4-5 / 195 M //
TU 05. 12Z: W 5-6 / 6-7 2 M //
WE 06. 00Z: SW-W 4-5 / 1.5 M //

Telephone services

Because of lack of demand, UK Met Office recorded telephone and telefax service have been discontinued. However, it is still possible to speak to a forecaster.


The BBC Radio 4 shipping forecast with its 6-hourly updates is a must – if you can hear it. MRCC VHF are valuable while near the coast but will not be received once over about 30 miles out to sea.

For a comprehensive list of available services go to my [Marine radio forecast page.

What to look for

Start a few days before you want to depart and study the forecasts on an ongoing basis. Compare the forecasts produced on one day with those on the next day and look for inconsistencies or trends. Inconsistency implies uncertainty in the outcome. A trend such as an acceleration of the collapse of a high suggests that the forecast is struggling to keep apace of changes in the current general pattern. Both situations require caution. Use the ideas given in a “How to use forecasts page”.

Having decided to go, then keep monitoring the forecast using the Radio 4 BBC LW Shipping forecast, INMARSAT-C, or NAVTEX from CROSS Corsen and la Coruña. Take each and every forecast, make notes of voice broadcasts - do not trust to memory.

A major strength of the BBC LW broadcast is that each forecast uses all the latest data including output from the 6-hourly runs of the Met Office operational numerical weather prediction model. Even fairly small changes from what was previously expected should be watched with care. The changes may not affect your area. But, they just might. Be that little more alert. While in range listen to the Inshore Waters broadcasts by the CROSS stations. If you have SSB radio then take the Radio Fax or the RTTY broadcasts.

All the time be on the lookout for any changes in emphasis or suggestion of uncertainty in the forecast. If you are unsure then consider diverting - say, to Gijón if your destination was la Coruña, or to Santander if Gijón had been in your sights.

Other Hazards

The firing range off the coast south of the Gironde can be a problem but the Capitaineries at Royan and Arcachon, or Cap Ferret semaphore, will advise or give you a telephone number to call. We have found that Cap Ferret is the best bet. A night time passage down the coast to or from Arcachon is always (I think) possible as are weekend day time passages. The advice of a French skipper for day time passages was "always check.” Even in August the range can be in operation.

God drew this bit of coast line on a Mercator's projection chart with a ruler and, visually, it is just as interesting. We prefer to do it by night in two bites to/from Arcachon where entry MUST be in daylight as the buoys are not lit. At worst, the weather and the firing range activity can mean waiting for a few days before proceeding. This is hardly a penalty as there is much to see and do. For example, Rochefort, up the Charente is well worth a few days of anyone's time.

On all Biscay crossings, ships and fishing boats are an ever present problem. I have never done the direct "outside" passage but would have expected ships transiting between the Ushant and Finisterre TSS to be a constant worry. We have had few ships on the routes to Bilbao, Santander, Gijón or la Coruña. We have only had substantial numbers of fishing boats at the northern end of crossings Santander to or from the French Islands.

If departing or arriving at Ile d'Yeu, then be sure to give the Rochebonne Plateau a wide berth. It creates a rough sea for some considerable distance around it.

And finally..................

Remember the old adage about there being “Old sailors, bold sailors but few old, bold sailors.” I have sailed in both directions around the coasts up and down to Santander via Royan, Arcachon, St Jean de Luc and San Sebastian. I have crossed Biscay from Audierne once to Gijón and once to la Coruña. I have crossed once to Santander from Ile d'Yeu and twice from Santander to Ile d'Oléron. My age is a matter of perspective. My grandchildren think that I am very old! That is as may be, but I am far from bold!

This was published as an article in PBO in August 2002. This version includes the use of GRIB products and has been reviewed after a Biscay Section day at the Cruising Association.