April is one of Casablanca's most agreeable months. Daytime highs around 20°C, freshened by the ocean breeze, make for comfortable all-day sightseeing under mostly bright skies, and the wet season is firmly behind. The seafront — the Corniche, the mosque esplanade, the long Atlantic horizon — is at its most enjoyable, and the city still feels uncrowded compared with the headline tourist hubs inland.
It is a fine month to take Casablanca slowly and on foot. A guided morning inside the Hassan II Mosque, an Art Deco walking circuit through the centre-ville, the Habous quarter's arches and bookshops, and a seafront lunch all fit comfortably into bright, breezy days. The light off the ocean is clean and clear, excellent for photography along the waterfront, and the evenings are mild enough for an easy stroll without a heavy jacket.
April also slots neatly into a spring Morocco itinerary, with the imperial cities and the coast both at their best and Casablanca's airport and trains making it an easy hub. For travellers who want the city's cultural depth with reliably pleasant, dry weather and few crowds, April is a strong, comfortable pick.