Because of the storms and dangerous squally conditions created in winter by localized meteorological phenomena, because of the strong northerly winds prevailing in that season, and because of the hazards caused by reduced visibility to coastal and celestial navigation as a result of overcast skies and fogs, commercial shipping generally avoided navigation in the winter whenever possible. This remained true from antiquity through to the sixteenth century. Naval warfare and piracy or privateering, the guerre de course, were also normally suspended. However, this suspension of maritime activity in winter was certainly never absolute. Neither did the degree to which seafaring was suspended remain uniform across the centuries. As a result of improvements in both ship design and in navigation techniques, particularly in the thirteenth to fifteenth centuries, the sailing season extended gradually back into early spring and forward into late autumn. By the sixteenth century it was far longer than it had been in the Roman, Byzantine, and Crusader periods.

In Boeotia of the eighth century BC, Hesiod, admittedly a landlubber, limited the safe sailing season to a mere 50 days in mid summer after the summer solstice; that is, from c. 21 June to c. 10 August, although he did admit a short but dangerous sailing season in early spring.