Boating in Greece: the best day to go

From June into September the meltemi sets the calendar. It comes down from the north, often for three or four days at a time, and it does not care that the sky is cloudless — the Cyclades can be blowing hard under perfect sunshine. The question is never whether it is a nice day. It is whether today is a crossing day or a day to stay in the bay and swim.

Bonasea answers that leg by leg rather than island by island. A run with the sea on the quarter is a different afternoon from the same distance across it: in the effective wave, beam seas count most, head seas less, and a following sea least. The ten-day outlook shows which days open up, every hour in your departure window is compared side by side, and the lee of the islands is taken into account, so the sheltered side of a channel is not scored as though it were open sea.

Depth figures are modelled averages rather than a survey of your bay, and the comfort score is an estimate from weather models rather than a promise. Bonasea does not replace official charts, publications, regulations or the skipper’s judgement. Read the warnings for these waters before you leave, and trust your echo sounder over the app.