It depends how high up you're going, and when. Obviously the winters can get very cold in the high Atlas.
But assuming you're going soon (this autumn) and because it's a day trip you're not going very deep (high) you won't need super-warm clothing. But the conditions are unpredictable with cold wind and rain likely, so take a waterproof jacket/parka.
Treat it like you would any mountain trek - always be prepared for any eventuality.
Phil. about 7 years ago
The weather is impredictibe in the Atlas Mountains. Better to get ready for the rain and chilly temperatures. However, the Atlas Mountains are not only one range but 3 and each range has its own temperature. . But I assume you're going to Imlil in the Toubkal National Park where it gets very cold at night. Ifyou're tarvelling with a travel company, most of them use guesthouses and you shouldn't worry about the temperature but bed bugs! Get prepared about 7 years ago