The Offshore Voyaging Reference Site

Q&A: Picking A Weather Window For A West To East Atlantic Crossing

Question: I’m planning an Atlantic Crossing from Boston to Scotland. How can I recognize the best moment weather wise to leave for the safest crossing?

Answer: Since weather forecasts are only accurate for about four days, at best, there is no way to manage the weather for an entire crossing of that length by picking a given day to leave. This means that you and your boat should be capable of withstanding at least one multi-day gale and on that route there is the possibility, albeit small, of a full blown North Atlantic storm, even in summer. (For more details on the best months to leave, see Best Time for West to East Atlantic Crossing.)

Having said that, you do want to try and pick a leaving date that will give you several days of good weather and fair winds so that the crew can settle down and get their sea legs. (See this article for more on our thinking about managing crew comfort.)

Generally the best departure days from the US east coast are immediately, and I do mean immediately, after a cold front goes through. This will normally give you clear weather and northwest winds as the following high pressure moves in. Of course this is based on averages and should not be taken as gospel.

You can also get a feel for how the systems are moving by analyzing the 500mb (jet steam) reports for several weeks before you leave; but to do this you will require an in-depth knowledge of weather theory and forecasting. A good idea anyway since you will have a much more comfortable, and probably safer, trip if someone on the boat has this level of knowledge and you install the necessary equipment to receive GRIB files and weather maps.

To gain a good grounding in weather theory, we recommend the Starpath Weather Trainer, an excellent computer based program learning package.

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Dick Stevenson

Although by this point, I would hope the writer of the question would have enjoyed a great Atlantic passage and landfall in Scotland, I will add a suggestion or 2 for others who may be entertaining the same question in addition to John’s excellent advice.
Firstly, I would urge anyone who is looking for the “best moment” anything to cut themselves some slack and look for a “good moment” or a good weather window. “Best moment” quests can be immobilizing. (Go to some of the favorite staging anchorages for crossing the Gulf Stream to the Bahamas, for example, and watch the collective anxiety build as some look for the perfect window.)
Secondly, if you have SSB capability (which I would recommend for an Atlantic crossing) listen to Herb Hilgenberg “Southbound II” (google for particulars) as he routes many dozens of boats doing Atlantic passages each day (an inexpensive short wave receive only radio will also suffice). Listening for the weeks ahead will give you a good feel for the weather patterns prevailing and is a weather forecasting education in itself. Listening will also educate you as to the protocols Herb likes to adhere to as he routes hundreds of vessels on passages for free. He has routed us wonderfully for years.
It is also likely that Herb will be talking with someone else looking for the same or similar window as you and who you can link up with, if you have SSB transmission capacity. When we left Bermuda for the Azores, we had a SSB sked with 4 other vessels and picked up some others coming from the mainland before we all congregated and met face to face in Flores.

Dick Stevenson

John, Yes, I agree. It is hard to know where to draw the line when Herb, Chris Parker, Commander’s and others are so ubiquitous and easily available. I am still impressed by how often, after almost 10 years of full time live-aboard and much paying attention to forecasting skills for wx, I can look outside and see what I see, and then look at a surface analysis and be bewildered about how these conditions evolved out of that analysis. Let alone 3 days hence. At some disciplined time in my life, I want to do forecasting on a daily basis from material available on passage and compare with actual events. Sort of like working sextant shots and then comparing with GPS.

Dana Marlin

I am going to be sailing from St Johns, Newfoundland to Iceland in July 2013. I am interested to know if anyone has replaced Herb Hilgenberg since I understand he has stopped his weather forecasting broadcasts? Are there any other SSB forecasters for this route?

I would also appreciate contact from any other boats planning this trip around the same time so that we can exchange information via SSB on route.



Thanks for the info John. I checked out Commander´s Weather but their rates are out of my budget. I was just hoping to be able to tune into some SSB station on route and hear what was in forecast. I am not looking for interaction or route planning advice. My range of transmission is not great and it uses a lot of battery power (I only have a small boat with limited electrical capabilities).