Sidi Ifni is pleasant year-round, tempered by Atlantic breezes that make it cooler than the interior and protect it from the worst of the summer heat. The trade wind from the north also makes it a reasonable destination in summer when the rest of southern Morocco is brutal.
The Sunday souk is the weekly highlight and worth timing your visit around — it takes place on the old airstrip on the edge of town and draws traders, musicians, and storytellers from the surrounding countryside. It runs from early morning and winds down by midday.
The surf is best in autumn and winter (October through February), when Atlantic swells are consistent. The beach is long and receives swell from the north; it is not a learner-friendly break.