Teleporio™ — Greek Island Travel Intelligence

Beaufort Scale Guide for Greek Ferries

Understand the Beaufort scale and what it means for Greek ferry crossings. When to sail, when to wait, and how Meltemi winds affect the Aegean.

The Number That Runs Greek Ferry Travel

Imagine you have booked a high-speed catamaran from Santorini to Mykonos for 14:00 on August 12th. You checked the schedule. You bought the ticket. You packed light. But you did not check the Beaufort. By 11:00 the harbour is white-capped. By 13:30 the port authority has suspended high-speed services. Your crossing is not running.

This scenario plays out across the Aegean thousands of times every August. It is not bad luck. It is the Meltemi wind doing exactly what the Beaufort scale predicted it would do — at exactly the time of day it always does it. The Beaufort scale is the difference between a traveller who arrives and a traveller who waits.

What Each Number Means at the Jetty

Beaufort 0–3 — The Teleporio green zone: Calm to gentle breeze. Mirror-flat to small wavelets. All vessels — overnight ferries, catamarans, small inter-island caïques — operate without restriction. This is when a well-chosen route scores 85–95 on Teleporio. Book any vessel, any departure time, with confidence.

Beaufort 4 — First signs: Small to moderate waves with white horses. Large Blue Star overnight ferries continue normally. High-speed catamarans on longer exposed crossings start to pitch. The Teleporio Score applies a 5% sea-state reduction to catamaran routes at Beaufort 4 — noticeable in the Score, noticeably felt on a longer Cyclades crossing.

Beaufort 5 — Catamaran threshold: Moderate waves, spray, many white horses. Large conventional ferries continue. Catamaran services on exposed routes — Santorini to Mykonos, Piraeus to Santorini high-speed — face cancellation risk. Teleporio applies a 30% penalty to catamaran scores at Beaufort 5. A route that scored 90 at Beaufort 3 now scores around 63. The Score is telling you something.

Beaufort 6 — Act on it: Large waves, white foam streaks. Most catamaran services suspended. Conventional ferries continue with noticeable rolling. Teleporio applies a 30% penalty to catamarans and a 5% penalty to conventional ferries. If you see Beaufort 6 forecast for your departure time, switch to the conventional ferry or move to the morning sailing.

Beaufort 7+ — Wait: Near gale and above. Port closures across most Aegean routes. Any route in these conditions returns a Teleporio Score below 50 — "High Risk". If the forecast shows Beaufort 7 on your travel day, plan the buffer day and find somewhere good for lunch. The sea will settle.

The Meltemi — Predictable, Not Unavoidable

The Meltemi is the prevailing summer wind of the Aegean — a sustained north-northwest wind that establishes from mid-July and peaks through August. It is not a storm. It is structural: it builds through the morning, peaks in the afternoon (typically Beaufort 5–7 on central Aegean routes), and eases overnight. Predictable, regular, and the single biggest determinant of ferry reliability in summer.

This predictability is what makes it manageable. Morning crossings — departures before 10:00 — consistently see calmer conditions on Meltemi-exposed routes. The same Santorini-to-Mykonos crossing that is cancelled at 14:00 often runs smoothly at 07:00. Teleporio accounts for this by scoring conditions at your specific departure time, not just a daily average.

How Beaufort Feeds the Teleporio Score

The Score engine applies vessel-specific sea state penalties that reflect how different craft actually behave in conditions. A caïque (short inter-island boat) scores zero at Beaufort 5 — it will not run. A catamaran at Beaufort 6 takes a 30% penalty. A conventional overnight ferry at Beaufort 6 takes only 5%. An airplane is unaffected below Beaufort 7.

This means the same physical route — Kos to Kalymnos, for instance — scores very differently depending on whether you take the 15-minute caïque (cancelled at Beaufort 5) or the conventional ferry (still running at Beaufort 6). Teleporio shows you both options, both scores, on the actual forecast conditions for your crossing day. That is the comparison that keeps you moving.