When we visited in January we did bring a couple of warm clothes with us - which turned out to be a good idea! It was nice and warm during the day, but in the evenings when the sun had set it was rather chilly!!! And if you are in the nearby Atlas mountains it gets cold quite a bit as well because of the altitude!
We were lucky that the sun was shining most of the time, but rain is quite common (at least in January)
Clothing/Shoes/Weather Gear: I take my travel mac with me everywhere I go usually, but, to be honest, Agadir was so hot and we reasoned that it was bound to be even warmer in land.... When we first arrived in Marrakech it was throwing it down and bitterly cold - especially as we were only wearing jeans and t-shirts! So - Be Warned! - bring light rain gear when travelling to Marrakech as you never know when the weather may change!
Rainy season: rainy season begins in September and lasts unill March; it hardly rains in the summer
Avg. Temp. in Spring: max.: 25 – 28°C ( 77 - 82°F ); min: 11 - 15°C ( 51 - 59°F )
Avg. Temp. in Summer: max.: 34 – 36°C ( 93 - 97°F ); min: 18 - 22°C ( 64 - 72°F )
Avg. Temp. in Autumn: max.: 23 – 34°C ( 72 - 93°F); min: 11 - 19°C ( 51 – 66°F )
Avg. Temp. in Winter: max.: 18 – 22°C ( 64 - 72°F); min: 7 - 9°C ( 45 - 49°F )