PHUKET WEATHER

Phuket is hot and humid throughout the year. The high season is generally considered to be from November to May. During the summer monsoon season, mornings and afternoons are still sunny and clear, but it tends to rain in the evenings and water clarity goes down. Locals consider May to October the "cool" season, and the weather is quite tolerable, much more so than in the tourism centers around the Gulf coast. It's comparable to Florida's summer weather in temperature and intensity of rain storms: 25-33 deg C, flying clouds, short and thunderous rainfalls in the afternoons and evenings.
All in all, there’s no bad time to visit southern Thailand. The southwest monsoon season isn't as bad as you might think. The skies are often clear and the seas moderate. There's really no reason why the southwest monsoon should interfere with a good paddling vacation. In sum, if you like cheaper prices and potentially wilder weather, come in the low season. If you like clear weather and predictable conditions, come on over in the high season.
By far the best time to visit is from December to March when the weather is kind and the beaches are at their finest.
The weather in Phuket has three distinct seasons:

The hot season from April to May

The wet season from June to October

The cold season from November to March

Below is a graph with the average high (blue) and low (purple) temperatures for Phuket taken over a 10 year period.


Below is a graph with the average rainfall for Phuket taken over a 10 year period