The Mistral: a turbocharger for experienced sailors

The Mistral is a strong cold wind that enters the Mediterranean from the northwest via France. It is a wind full of contradictions — a friend to experienced sailors but a foe to those just starting out, a destroyer of crops yet creator of fabulous sunny days in Provence. So how can it impact your sailing vacation? 

How does the Mistral form?

Like many other typically Mediterranean winds, the Mistral is primarily a local wind with its origin and course influenced by the specific terrain and local climate. It occurs when an area of high pressure (anticyclone) forms in the Bay of Biscay in western France and an area low pressure (cyclone) forms around the Gulf of Genoa. The anticyclone then extends over land until it meets the area of low pressure from Italy. Due to the rotation of the Earth (the Coriolis Effect), both systems rotate in opposite directions and when they meet over France, it creates a powerful current of air that sweeps across the landscape, blowing full-force into the Gulf of Lion off the Côte d'Azur. 

The Mistral is most common in winter and spring, mainly as a result of low pressure systems from Italy. Around the Bay of Biscay, the pressure is always higher because of its proximity to the tropical belt and consistent warming of the air by the sun. The temperature of the Mediterranean doesn't vary dramatically throughout the year either, but in the mountains the temperature drops noticeably in winter. It is this difference in temperature that causes the low pressure system to develop, which together with the Atlantic anticyclone forms the Mistral. But an occurrence such as this is not unusual and happens all over the world. So what makes the Mistral different and what gives it such great speed?

Where does the Mistral get its power? 

The Mistral is cold and heavy in winter with gravity pushing it down. Still reaching heights of up to 300 m, it picks up colder and heavier air from the mountains and hills of France along the way, making it even heavier. And this is where the terrain comes into play. Along its way, the Mistral funnels through mountain passes and river valleys, compressing it and reducing friction. These areas act as acceleration zones, giving rise to some hellish speeds.  

The Mistral can easily pass through at speeds exceeding 65 km/h (equivalent to a Beaufort 8), reaching its highest speed of around 180 km/h (Beaufort 12) in the French Rhône valley. It is this that makes the Mistral such a dangerous and destructive wind that can knock down trees and destroys crops, in stark contrast to the usually calm cloudless weather of Provence.

Croatia has local mistral winds

Surprisingly, you can also encounter local mistral winds in Croatia (especially in the southern Adriatic). However these winds are quite different from the French Mistral and are caused by the difference in sea and land temperatures. Said to follow the path of the sun across the sky, these winds don't begin to form until the afternoon when the water has warmed up. As they are not so large, powerful and destructive, and with their strength growing gradually, they provide plenty of time to find safe harbour. 

However, in the sea between Hvar and Vis or Korčula and Lastovo, these winds can also cause large waves and pick up a vicious speed in the straits between Zadar and Ugljan, Brac and Hvar, Korčula and Pelješac. Also these local mistral winds commonly form during the peak sailing season, in July and August, which can be an unpleasant surprise for holidaying families and novice skippers.

The Mistral wind does not come alone

The Mistral is occasionally joined by its Spanish counterpart, the Tramontane, which forms and behaves in a similar way to the Mistral (which is why they sometimes get confused). The Tramontane gathers its strength in France a little further south in the corridor between the Pyrenees and the French Massif Central, as well as further north from the Italian Alps. Crossing the Mediterranean, you may encounter some of the other infamous Mediterranean winds, or at least their milder local forms. The Mistral itself is the north-westerly counterpart to the Croatian Bora. Both are extremely strong cold descending winds, at their strongest from late autumn to spring. However, the Bora has the nasty habit of coming in gusts, and can reach speeds of 250 km/h.

The Mistral: great to sail, but...

For experienced skippers, a mistral of up to 4 or 5 degrees on the Beaufort scale can be a friendly breeze, propelling the sailboat forward at a brisk, steady pace without unpredictable gusts. Especially when sailing on a tailwind or broad reach to the south, southeast and possibly even east. From Marseille, under the influence of Italian cyclones, the Mistral turns towards St Tropez and beyond to Corsica and Sardinia.

Keep in mind, however, that the Mistral grows more powerful during the day and reaches its peak in the afternoon or evening, so may take you by surprise just an hour or two after setting sail. Like any wind, it's also gustier and faster on the open sea, as there's no significant friction to slow it down. Even experienced sailors may not be comfortable sailing there as it creates short waves that are difficult to sail even using the motor. These waves can reach 5 to 7 metres, which will probably make your crew seasick.

Only large cruise ships can handle higher forces on the Beaufort scale. So don't take your sailboat out to sea, rather spend a few days on land enjoying the local culture. In the winter months, we don't recommend sailing against the direction of the Mistral (even if it's not blowing yet). The voyage will be more demanding and longer because you'll be beating against it and may not be able to return the boat in time.

YACHTING.COM TIP: Prevention is always the best defense. It is better to underestimate your skills and those of your crew than overestimate and then have to deal with a storm at sea. Don't forget to practice the MOB (Man Over Board) procedure. From experience, we've found that it's a fun yet practical way to kill time with your crew when the wind is light. And a proper life jacket is a must.

Could the Mistral jeopardise your vacation?

This is not likely in high season. The French Mistral winds do blow then, but they are more of a pleasant breeze to refresh you on humid days. Between November and April, the risk of encountering winds stronger than 6 on the Beaufort scale is about 30 % higher. In summer, it's around 18 %. The Mistral usually lasts no more than 2 to 3 days and rarely stretches out for a whole week so you can just wait it out for a few days in port. Unfortunately, you probably won't get to enjoy your free time so much as the wind will be uncompromisingly driving you from the picturesque streets back to the boat or into the nearest pub. That is unless you join the local windsurfers, who always have a smile on their face when they see us sailors having to moor our boats in the harbour. You'll probably have to adjust your itinerary and settle for a shorter voyage. In a weaker mistral, it might be possible to sail south along the coast to Spain but here too, you should keep a close eye on the forecasts so that the Tramontane can't take you by surprise.

Be prepared for various types of weather:

Where to sail and anchor during the Mistral

In all honesty, as the Mediterranean is bordered by mountains along most of its perimeter, if it's not the Mistral you encounter, it will be the Sirocco (or Jugo in Croatian), the Bora or some other wind. So there is no reason to deprive yourself of the magic of autumn sailing. You just need to be honest about your own skippering skills and choose your location well.

For beginners and less experienced captains, we would not recommend being on the water at all during the French Mistral. These winds can give even the most experience sea dogs a run for their money. In the summer months, on the other hand, it can be nice to have a weaker mistral at your back when sailing around the little-known island of Capraia or nearby Elba. The island of Elba even offers information on its website about beaches sheltered from the Mistral. You can also check out the volcanoes of Sicily and the Aeolian Islands. 

Advanced sailors can use the weaker Mistral as a turbo boost to sail around the untamed and distinctive Corsica or the Caribbean-like Sardinia. The term turbo boost is quite appropriate here as the western Mistral often joins forces with its contemporaries, the Ponente and Sirocco, together crossing the Strait of Bonifacio between the two islands. But even in the north of Sardinia you will find several anchorages well-sheltered from the Mistral, such as Porto Pollo or the marina at Porto Pozzo. The south of Sardinia promises a wonderful sailing too and we have a complete article on the topic with routes and tips for excursions.

YACHTING.COM TIP: Practice port manoeuvres regularly and right from the start to ensure that each crew member knows exactly what to do. For anchoring at sea, learn this trick to make sure the anchor holds securely even in the toughest conditions. The so-called Mediterranean Mooring technique might also come in handy, which you can use wherever you need to back up to land astern with no other way of securing the boat. 

Can the Mistral be predicted?

You will get some warning before the Mistral arrives but not far in advance. If you're near the coast, a few hours will be enough to find a safe harbour, but in the open sea you'll have to wait it out. Keep a close and regular eye on the forecast on the Windy app or whichever app you use and on the behaviour of French anticyclones and Italian cyclones on synoptic charts.

Fortunately, as the Mistral is also a concern for people on the mainland, local radio stations, TV and online media carry forecasts. Information also spreads along the coast via radio (VHF) and this is often in English. 

There is also folk meteorology to follow by looking up in the sky for lenticular clouds — a cloud resembling a lens or UFO. This should appear the day before the Mistral arrives. The sunset should turn from golden to pink and then to grey with bits of red. It is said that the faster the clouds turn grey, the stronger the winds will blow. After dark, the first gusts of wind will start, with the intervals between them shortening as the night progresses.

YACHTING.COM TIP: As soon as the Mistral stops blowing, expect a change in the weather. As long as it blows, it has enough power to keep the clouds at a respectful distance. You can often see a cluster of clouds waiting patiently behind Marseille, ready to invade as soon as it passes.