Windhosen (waterspouts) on the water are indeed a rare weather phenomenon, yet skippers traveling with their yachts in Europe can still be confronted with them.
“Spectacular waterspout and first snow of the year: Winter onset in Mallorca“, reports the Mallorcazeitung on November 21st; up to three centimeters of snow fell, and an “impressive Cap de Fibló” (a waterspout) occurred over the sea, which could be seen from Sóller and Deià, among other places. (Facebook video)
Only in August, a rare weather phenomenon also occurred on the Baltic Sea: off Hiddensee, an “impressive waterspout” formed, reported the NDR; the spectacle was short-lived but visible from afar. The waterspout formed on the Schaproder Bodden (district of Vorpommern-Rügen) and whirled up water. (Video on Facebook)
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A windhose — often referred to as a waterspout over water — is a swirling column of air or air/water extending from a thunderstorm or cumulus cloud to the water surface. Basically, a distinction is made between two main types: non-tornadic waterspouts (“fair-weather waterspouts”) often form over relatively calm water, with little vertical wind shear, within the framework of small convection usually without strong supercells. Tornadic waterspouts, on the other hand, more closely resemble classic tornadoes, are far more dangerous, and often occur in the context of strong thunderstorms or supercells.
A prerequisite for the formation of a waterspout is warm/moist air over the water
An important prerequisite for the formation of a waterspout is warm/moist air over the water; rising air (convection) is thus possible. Instability (e.g., colder air above, warmer water below) and possibly diverging or converging winds near the ground or water surface, or wind shear, is also a conceivable scenario for rotation to build up. The resulting vortex then develops under a cloud base (often cumulus or cumulonimbus) and often reaches down to the water surface, where it can sustain itself longer than on land because friction is lower on the water.
Important: Waterspouts do not only exist in tropical regions; they also occur in Europe. About 160 waterspouts are documented annually for the European area, e.g., in the Netherlands, Spain, Italy, Great Britain. There are also studies for the North and Baltic Seas: for example, in the region around Heligoland, there is approx. one event per year, measured per 10,000 square kilometers of area. In the Mediterranean region – e.g., off the coasts of Italy/Sicily – it is stated that waterspouts are more frequent, especially towards the end of summer or the beginning of autumn (warm water surface + tendency for thunderstorms).
Most recently – beyond the aforementioned events – waterspouts were observed in Europe, for instance on March 12, 2025 (trombe marina) off the coast of Biscarrosse (Landes, France); on August 1, 2021, several tornadoes/waterspouts were observed near Istria/Croatia (SeaHelp reported here). Furthermore, a study in 2002 documented waterspouts in the Adriatic/Ionian/Aegean Seas, specifically in the period from July to November.
When traveling by boat as a skipper, a dark spot or ring on the water surface or spiral patterns in/on the water can serve as warning signs, in addition to a currently developing funnel or tube cloud between the water surface and the cloud base. Sudden wind and pressure changes, noticeable wave patterns, or weather conditions with lighter wind over warm water + converging winds can also serve as warning signs.
At sea, skippers should immediately change course and gain distance
In this case, skippers should immediately change course and gain distance. If the waterspout is following a relatively straight path (which will rarely happen and is uncertain to predict), it is best to move away at a right angle to the direction of the waterspout’s movement – so much for the theory.
The practical advice of a SeaHelp member from Pöllauberg/Austria, who according to his own statements was already able to evade a waterspout twice “at short range”, has had good experiences steering towards “where there is clear sky without clouds” and “immediately fleeing under sails and engine”.
If there is no longer a chance to evade, one should – if there is still opportunity – attempt beforehand to reduce the surface area exposed to the wind and the vortex itself by taking down the sails and lashing them tight, or at least reefing them. Additionally, the engine should be made ready to keep the yacht maneuverable. Loose objects on deck should be secured, and hatches should be closed.
Under no circumstances should one attempt to “scout” the waterspout or drive close to it – this behavior poses an avoidable risk. Should the situation require it, the port authority or coast guard radio should also be informed about the situation if possible.
Note: Even if many waterspouts are only moderately strong, the gust of wind or the carried spray or falling amounts of debris/water can nevertheless quickly lead to critical situations on deck.
Where is the yacht safer – in the harbor or on the open sea?
In this context, the question is often asked where the yacht is safer in such a situation – in the harbor or on open water? The answer to this question depends heavily on the respective context. A harbor has the advantage that the boat has a stable berth here, it is moored, movements and rudder deflection are limited. In the harbor, there is often also better protection against large-scale wind and wave events, at least in direct comparison to the open sea. Access to assistance and equipment is also easier here.
In the immediate vicinity of harbor facilities, however, there may be a risk of injury from floating debris, other yachts, or moving parts. If the harbor is poorly protected (e.g., if there are no breakwaters), a waterspout can also cause great damage near a harbor. And: in the harbor, one may be less mobile – evasion, which might be sensible depending on the situation, is more difficult.
On open water, on the other hand, the boat has better maneuverability, and one has the necessary space to potentially evade in time. Furthermore, out at sea, there is no immediate danger from harbor facilities or too confined surroundings. On open water, skipper and crew also have the possibility to react actively to weather events (change course, drive away from the event).
However, an open environment usually also means a larger surface area exposed to wind and waves. If the boat gets into the effective range of a waterspout, one is on one’s own, and a “retreat” can be difficult; if caught at the “wrong moment”, the situation can quickly become dangerous (dismasting up to capsizing).
Conclusion: as a general rule of thumb, it can be said: if the boat is already safely in the harbor, and the weather situation (e.g., announced thunderstorm situation with the possibility of waterspouts) suggests it, then the harbor can be the safer choice in many cases.
However, if one is already at sea with the boat/yacht, and a waterspout is actively occurring or threatening to occur, open water with enough space to evade is often the better option than trying to enter a (possibly poorly protected) harbor under time pressure.
Crucial in any case are forward-looking action, observation of the weather situation and an assessment as realistic as possible of the protection options in the harbor or the maneuverability at sea.
