Sorry if this is stating the obvious but...

It's possible to get relief from the heat in a day by gaining height in Morocco, roughly 2c drop per 1000ft rise (7c drop per 1000m)

Tafraoute 1000m
Nekob 1700m
Ilmilchil 2300m

The 32deg 4 week figure happens to stick in my mind, I'd just got a little weather station thingy that stored highs and lows. And that the LCD blacks out at 60deg C cab temps :(

I do remember finally heading west towards Agadir, the temperature dropped about 10degC in an hours driving, going from bonkers to comfortably hot. We weren't sure how much the temp would change, but it was so much better we kicked ourselves for not doing it sooner!

Gee, it's amazing how people assume that Morocco = sand and dunes. As mentioned, the Atlas mountains are fantastic for riding, there's so much to do there! And you certainly don't want to go there in winter, I had snow on a pass last March. And the Mediterranean coast sure isn't going to attract people during the cold and wet days.

In Merzouga in March this year it was a little coldish for me in the evening when having a sundowner beer, but just great when riding hard.

There just isn't one "good" time for the whole of Morocco. YMMV.

Morocco
 

Heading to morocco July 2013. Leaving from Dublin on 23 July and meeting mate in London and then on to morocco. Happy to meet up with like minded travellers for some of trip.
Let me know if you are interested
Thanks