Two things rule Menorca's climate: the sea, which softens, and the tramuntana, the north wind that can turn up in any season and that shapes the island. The south, sheltered, is almost always calmer than the north. And the swimming season is shorter than in the Canaries: the water isn't truly pleasant until June and holds up until well into October.
Spring and autumn: the secret
May, June, September and October are, for many, the best: good weather, a green island, coves without stress, comfortable hiking on the Camí de Cavalls and gentler prices. In May the water is still fresh for a proper swim, but September is perfect: warm sea, fewer people and golden light.
Summer: turquoise and full
July and August are guaranteed sun, warm water and the coves at their peak — but also full car parks, packed coves and high prices. If you come in August, rise early for the coves, book the boats ahead and move at first and last light. The reward is that impossible turquoise.
Sunset Catamaran Tour from FornellsCheck availability →Sant Joan, the fiesta
On 23–24 June, Ciutadella gives itself over to the Sant Joan festival: the black Menorcan horses rear up amid the crowd in one of the most impressive celebrations in Spain. If you can line your trip up with those dates, do it — but book accommodation well ahead.
There's no bad time for Menorca, only the one that best fits your plan. If you can choose, aim for the edges of summer: you'll get the island at its best — green, quiet and with the water just right.