Diego in the north: plage d'émeraude. Very strong wind during summer time, 35 knots everyday. The bay is inshane.
Tuléar in south : take taxi to go 20 km north of the city, a lagoon called Ifaty, 3km large lagoon, you will be alone. Less strong wind than in the north. You have several hotel there. Wake up, and the wind generally start to blow at noon.
You have also thisin the south, I didn't try.
www.mada-surfaventure.com