September is one of Casablanca's finest months. The warmth of summer lingers — highs around 26°C — but the grey morning haze fades, leaving clearer, brighter days, while the ocean is at its warmest after a season of sun. The peak-summer crowds thin out, and the seafront settles into a relaxed, pleasant rhythm. It is genuinely excellent timing for the city's coast and culture alike.
With the mornings clearing, the whole day opens up. The Corniche, the Ain Diab beach clubs and the Hassan II Mosque's esplanade are all comfortable from early on, the warm sea makes swimming inviting, and the evenings stay balmy for seafront dining. Indoors, the mosque tour, the Habous quarter and the Art Deco downtown are easy in the gentle, breezy warmth — no inland furnace, no winter damp.
September also marks an ideal hub month for a wider trip, as the rest of Morocco eases out of peak heat. Rabat is an hour up the coast, the imperial cities grow comfortable again, and Casablanca's airport and rail links make it a natural start or finish. For warm, bright, uncrowded coastal days, September is among the very best times to visit.