The Meltemi, and What It Does to a Week Afloat

The meltemi is the strong, dry north wind that blows across the Aegean in summer, hardest in the Cyclades and most persistent through July and August. It builds through the morning, peaks in the afternoon and often eases after dark, and a single episode commonly runs 2 to 5 days before the next one. It rarely cancels a charter; it moves it. One side of an island becomes untenable while the other stays comfortable, and a captain who knows the water changes the route rather than the week.

What it is

The meltemi is a wind with a mechanism, which is why it is predictable in a way that most summer weather is not.

Through the Aegean summer, high pressure sits over the Balkans and low pressure over Anatolia. Air moves between them, funnelled north to south down the length of the sea. The result is dry, clear, cool and hard — the days people photograph, blowing at the speed people do not expect.

The ancient Greeks called it the etesian wind, from the word for annual, because it arrives every year. That is still the most useful thing about it. It is not weather that happens to a charter; it is a season the charter takes place inside.

When it blows, and how hard

The season runs from about mid-May to mid-September, and it peaks between mid-July and mid-August.

Figures from the Hellenic National Meteorological Service give the shape of a normal year: a 17-year average of 17 days of strong winds in July and 19 days in August.

The averages hide the real variable, which is the year rather than the month. The summer of 2025 produced 61 days of strong winds across the Aegean, the highest total in 17 years. A quiet August and a relentless one are both entirely normal, and no calendar published in January tells you which is coming.

Over open water the wind commonly runs 15 to 25 knots, with bursts stronger than that. It funnels and accelerates between islands, so the strait is always harder than the chart suggests.

What it does to a day

The daily rhythm is as reliable as the seasonal one, and it is what a good captain plans around.

Early morning is the lightest part of the day. The wind builds through the late morning, peaks in the afternoon, and frequently eases after sunset.

So a passage that is unpleasant at four in the afternoon is often untroubled at seven in the morning. Crews move early in a meltemi week — anchor up at dawn, arrive by late morning, and spend the afternoon somewhere in the lee. Guests who wanted a slow start find that the slow start is at the other end of the day.

What it does to a route

An episode typically lasts 2 to 5 days, and it does not blow itself out politely at the end of a charter.

What it changes is geography, not the calendar. In the Cyclades the north-facing bays become untenable and the south-facing ones stay comfortable. Ports on the wrong side of an island are unusable while a bay two miles away is glass. Mykonos and Paros in a hard meltemi are not the same islands they are in a calm week.

This is why a captain’s answer to a fixed itinerary is so often a qualified one. The exposed leg gets postponed, the run to the next island gets taken at dawn, and the night in a particular harbour becomes a night in the bay behind it. On a well-run week the guests notice mainly that lunch happened somewhere different.

The thing worth understanding before departure: the captain is not being unhelpful. Command of the yacht — and the decision about what is safe — sits with them, not with the charter agreement.

Where it does not blow

The Aegean is not all of Greece, and the meltemi is an Aegean wind.

The Ionian, west of the mainland, sits outside it almost entirely. The Argo-Saronic — Hydra, Spetses, Poros and the Peloponnesian shore — sits in its shadow and is markedly gentler. Both are perfectly serious cruising grounds, and both are where Aegean weeks quietly relocate to in a hard August.

The season itself offers the other answer. June and September carry far fewer strong-wind days than the fortnight either side of 1 August, with warm water and better light. The same islands, the same yachts, a different sea.

What to settle with the captain before the week

  1. Which legs are exposed, and what the alternative is for each one. Ask for the alternative by name.
  2. What time the yacht moves. In July and August, the answer that keeps the week comfortable is usually early.
  3. Which nights, if any, are fixed. A table ashore on a particular evening is a commitment the sea has not agreed to.
  4. What the yacht is like at anchor in 25 knots. Motor yachts and sailing yachts behave very differently, and so do guests.
  5. Whether the cruising area in the contract is wide enough to include the sheltered version of the week. If it is not, widen it before signing rather than after.