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. It is 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 but moves it: one side of an island becomes unsafe to stay on 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 known cause, so 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 and is funnelled north to south down the length of the sea. The result is dry, clear, cool and hard: bright days, with a wind stronger than visitors 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 to know about it. A summer charter takes place inside the meltemi season.

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 at 15 to 25 knots, with stronger gusts. It funnels and speeds up between islands, so a strait is always rougher than the chart suggests.

What it does to a day

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

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

So a passage that is unpleasant at 4pm is often smooth at 7am. Crews move early in a meltemi week. They raise the anchor at dawn, arrive by late morning, and spend the afternoon somewhere in the lee, the side sheltered from the wind. Guests who wanted a slow start find it comes 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 stop on time for the end of a charter.

It changes where a yacht can go, rather than the dates. In the Cyclades the north-facing bays become unsafe to stay in and the south-facing ones stay comfortable. Ports on the wrong side of an island are unusable while a bay 2 miles away is flat calm. Mykonos and Paros in a hard meltemi are very different from the same islands in a calm week.

This is why a captain so often answers a fixed itinerary with conditions. The exposed leg is postponed, the run to the next island is made at dawn, and a night in a particular harbour becomes a night in the bay behind it. On a well-run week the guests mainly notice that lunch happened somewhere different.

Before departure, it helps to understand that the captain is not being unhelpful. Command of the yacht, and the decision about what is safe, sits with the captain and not with the charter agreement.

Where it does not blow

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

The Ionian, west of the mainland, sits almost entirely outside it. The Argo-Saronic, which takes in Hydra, Spetses, Poros and the Peloponnesian shore, sits in its shadow and is much gentler. Both are serious cruising grounds, and Aegean weeks often move to them in a hard August.

The calendar gives the other answer. June and September have far fewer strong-wind days than the fortnight either side of 1 August, with warm water and better light.

What to settle with the captain before the week

  1. Which legs are exposed, and the alternative 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 booked ashore for a particular evening is a commitment the sea may not allow.
  4. How the yacht behaves 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.