Hi there!
I'm a Kite Surfer so always checking every place i visit. First of all. Forget Phuket for Kite-Surfing unless you want to learn and fly with a 20 sqm. Kite. (which is not fun, believe me...) The problem is: Theres just not enough wind around Phuket. Pretty much all the known Kite-spots around Thailand lack wind. (Phuket,Chumphon, Samui, Hua Hin).
The best time for Kite Surfing in Thailand is during the north east monsoon. Usually November till mid of January. And even then you have to cross fingers to get a decent breeze.
I will travel to SE Asia in just 4 weeks for a Kite-Holiday. I will visit Thailand (transit) and go to Vietnam. One of SE Asias Top Kite and Windsurfing Spots is Mui-Ne. Has perfect conditions till end of April.
Heres some Mui-Ne Video Footage on youtube:
YouTube - Mui Ne Madness
IF you need infos, pm me! I'm a Kite Addict!
hang loose,
banger_chris