There is a version of the Aegean that appears on postcards, and there is the Aegean as it actually behaves through the year — and the gap between the two is where a good voyage is won or lost. The islands do not have a single “best” season so much as a set of distinct ones, each with its own light, its own temperament, and its own crowd. Knowing which you are sailing into matters more than the ship you sail on.

What follows is how I think about the calendar when a client asks the deceptively simple question: when should we go?

Late spring: May into mid-June

This is, for most travellers, the quietly correct answer. The hillsides are still green from the winter rains, the wildflowers have not yet surrendered to the sun, and the sea has warmed enough to swim without bravado. Days settle in the low twenties Celsius — warm in the sun, cool in the shade of a taverna — and the towns have shaken off winter without yet filling to the brim.

The light in late spring is the thing people remember. It is clear and long and forgiving, the kind that makes whitewashed Cycladic villages look the way they do in your imagination. If your priority is walking the old towns in comfort and having a table to yourself at dinner, this is the window I steer toward first.

High summer: July and August

The peak season is peak for a reason, and I will never talk a family with school-age children out of the only weeks they can travel. But it is worth knowing what you are choosing. Midday heat becomes something to plan around rather than ignore; the marquee ports — Santorini above all — take on cruise crowds that can turn a caldera sunset into a queue.

There is also the meltemi: a dry northerly wind that funnels down the Aegean through July and August, strongest in the afternoons. It is the reason a morning of glassy calm can become a lively afternoon at anchor, and occasionally the reason a tender port is swapped at short notice. A good itinerary in high summer is built with the meltemi in mind — smaller, more sheltered islands, mornings ashore, and a captain who plans for the wind rather than against it.

Early autumn: September into October

If pressed for my own favourite, I would name September. The sea is at its warmest, having banked heat all summer; the meltemi eases; and the August crowds thin noticeably once the European holidays end. The days are still generous, the evenings begin to soften, and the whole region seems to exhale. It is the connoisseur’s month — all the warmth of summer, little of its congestion.

By mid-October the season is turning. The light grows lower and more golden, some island tavernas begin to close for the winter, and the first weather systems arrive. For a traveller who prefers atmosphere to swimming, it can be lovely — but it asks for a little more flexibility.

The quiet weeks worth asking about

The most rewarding sailings are often the ones on the shoulders of the season — the last week of May, the first two of October — when prices soften, the marquee ports breathe, and the islands feel, briefly, like they belong to the people who live there. These are the weeks I watch for on behalf of clients who can travel outside the school calendar.

None of this is meant to be prescriptive. The right week depends on what you want from the voyage — swimming or walking, quiet or colour, marquee islands or the ones no one has told you about yet. That is the conversation I would rather have than sell you a date. If the Aegean is on your mind, see what I have quoted this season — and tell me what you are hoping for.