Meteorologist and weather router, Chris Tibbs, takes a look at North Sea weather and tells you what to look out for if you’re crossing from the UK to the Scandinavian Peninsula
Dogger, Fisher, German Bight. Even the names of the North Sea weather forecasts are evocative, conjuring up a vision of faraway places frequented by Viking adventurers and epic seafarers. The North Sea is a large body of water and although narrow in the south opens out to give a significant sea passage if crossing from Scotland.
The Baltic is a popular cruising ground and passages to the Baltic can include the Frisian Islands and a re-enactment of The Riddle of the Sands (good reading for all sailors). A Scandinavian cruise has something for everyone, from tranquil islands of the Swedish archipelagos to the cultural heritage around the Baltic. Further north into Norway there are fjords and glaciers and high latitude cruising.
But what of the weather? The southern part of the North Sea is strongly influenced by the continental land mass, while the further north we go the more the maritime climate of the UK exerts its influence.
We are in a band of disturbed westerly winds, driven by the jet stream and a long precession of low pressure systems that will generally pass to the north-west. As we get further north and into these more disturbed westerlies the more the weather becomes like the west coast of Britain.
South of Norway is the area known as the Skagerrak, a strait running between the south-east coast of Norway, Jutland peninsula, Denmark, and the west coast of Sweden. Here the airflow is strongly influenced by the mountains of Norway and is an area of cyclogenesis, where lows will develop and deepen, often then drifting away to the east into the Baltic. This is not dissimilar to the Gulf of Genoa where lee troughs and lows develop in the shelter of the Alps.
In general, during the summer months, the frequency of gales is similar to the western part of the British Isles at 1-2% of the time, which increases in the Skagerrak.
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Gale frequency increases dramatically in September so it is best to be away by then. Further east in the Baltic the continental influence on the weather is stronger, with warmer weather and lighter winds.
Further north does bring some heavier weather, however the tail of the Gulf Stream (by the time it reaches the North Sea, usually called the North Atlantic Drift) keeps the area ice-free and relatively warm. This is quite a bonus as southern Norway is on the same latitude as the southern part of Greenland.
There are not always periods of depressions as high pressure will sometimes build (it even has a name; the Scandinavian High). High pressure over Scandinavia can stay for a number of days, or even weeks, and becomes a blocking high, stopping lows from crossing the area. This can push lows well to the north, or at times even south over Spain and into the Mediterranean.
Getting to and from Scandinavia can bring its own challenges. The North Sea is an interesting place to sail; in the southern part are some of the busiest ports in Europe, with Rotterdam topping the list but closely followed by Antwerp, Hamburg, and Bremen-Bremerhaven.
The southern waters of the North Sea are busy, and therefore strictly controlled with traffic separation schemes that tend to restrict where we can safely and legally sail. Throw into the mix wind farms, sandbanks, gas and oil rigs and it is no place for a first night passage! A refresher course in the Colregs is a good idea before a crossing.
The southern part of the North Sea also has its fair share of fog and poor visibility, with statistics indicating a likelihood of fog 3-4% of the time. However, fog is directly linked to the direction of the wind bringing warm moist air over the colder North Sea, so is generally linked with the wind from south-east through to south-west.
On one Round Britain and Ireland race we had predominantly south-easterly winds for the whole period and visibility was rarely above a few miles, and often foggy.
On the east coast of the UK whenever there is an easterly to south-easterly wind we can get sea fret, also known as harr. A warm, moist, generally south-east wind blowing across the North Sea cools over the colder water, which in turns brings fog to the east coast. This is advection or sea fog and dissipates a few miles inland but is a real problem when sailing near the coast.
The wind in the southern North Sea does tend to be a little lighter than further north. It also varies in direction from the north through the west to the south, as it depends on what systems are influencing it.
Heading north, the water deepens and there is more sea room. Being relatively shallow the sea state can become short and steep, but outside of winter the waves are not excessive.
If heading from the south coast of England and making for the Kiel Canal and the Baltic, crossing over to the Dutch side is the shortest route and, although busy with shipping, there are plenty of places to stay on the way. With generally lighter winds in the south some diesel may have to be sacrificed on the passage.
To cross to Norway distances are long: a passage from the Solent to Bergen of around 700 miles is the shortest route, this is further than heading across Biscay to Northern Spain. The shortest passage is Shetland to Bergen at under 200 miles, so little more than a day sail – but with a significant sail to get to Shetland beforehand.
If heading from the south coast I’d tend to coast hop around to Lowestoft, or somewhere nearby, then set off from there to Norway. This gives a passage of under 400 miles and keeps clear of the busiest shipping lanes. With predominantly westerly winds it should be a good passage of around three days. There will still be numerous oil rigs to dodge, however as they are fixed there are no excuses for getting too close.
I see little point in heading further north up the English coast as it adds miles for little gain. But it is rather different if coming from the west coast of the UK, options are either through the Caledonian Canal (something I have always wanted to do), or around the north of Scotland, calling at Shetland or Orkney – or both. This shortens the passage but leaves us exposed to stronger wind. This is most likely to be between north-westerlies to south-westerlies, varying as depressions pass through.
Returning to the UK can be a little harder as it is generally against the prevailing winds; for this passage I’d tend to head south first into what is usually slightly lighter winds before making my way back to the UK, or wait until I have a good weather window.
Particularly around northern Scotland and western Norway the chance of gales increases significantly in September which is a little earlier than further south. Tempting though it is to dwell in Scandinavia to make the best of a summer cruising, leaving later can mean a harder passage back home. I’d therefore be tempted to do my more northerly cruising early and then sail south to Denmark before working my way back home. If we have left it very late a passage late season east of Denmark and through the Kiel Canal is another possibility.
North Sea weather
• Depressions will generally pass to the north-west of Scotland
• Small lows can develop and deepen south of Norway before moving east
• The further north, the greater the effect of Atlantic low pressure systems
• Fog can be a problem in the southern North Sea, and along the coast of England and Scotland with winds from the south-east through to the south-west
• The chance of gales increases significantly in the north around northern Scotland and western Norway during September
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Source: Yachting World