Basically, Thailand has three seasons: a dry and hot season (from November until February), a very hot season (from March until the end of April; the weather is still dry, but very hot, and doing sightseeing tours may be uncomfortable) and a wet and hot season (this is the monsoon season from May to the end of October), and these distinctions also apply to Phuket. The best months for travelling are December, January, and February, but November, March and April are also acceptable (though the air is more moist and it may rain occasionally).
 

Clothing

You should dress for a tropical climate: cotton, silk or linen clothes are most comfortable. Exposing too much of your skin will not only earn you a sunburn, but is also frowned at by the locals. No  matter  how hot is is, gentlemen must wear long pants in urban areas. For ladies, pants are also o.k., or you can wear a skirt or a dress that covers the knees. Sleeveless shirts or sleeveless sweaters should also be avoided.  Beach wear is only acceptable on the beach! See also the  rules  for  temple visits.