best time to visit is around new years. weather is not as hot and the country wont be as crowded as in summer moroccans in europe come down for holidays too.

When is the hottest time of year in morcco?

Yeah, as lehcen noticed tourism peak occurs during summer. Best period I think is spring, where you can enjoy Marrakech, Fes and all the landscapes. But if you're looking for beaches then summer's the time to go!