Since weather is the biggest issue for many people - just for a start - you might want to check our Weather page for current weather, weather statistics and history and much more. 

During low season (summer and the rainy season) the island is quieter and traffic is easier - and accommodation prices are often half of high season fares.  Some people may be put off by the rougher seas and some beaches will have a strong undertow.  It is not always safe to swim as the sea reacts to the weather. Swimming for children in particular is probably not safe unless you seek protected waters on the bay side of the island.

  October to April (cold weather season in the northern hemisphere) is high season as people escape their harsh winters and flock to nicer climates.  

Some people suggest November to February as the high high season - when the island is its very busiest. If you enjoy the nightlife and crowds, it's a good time to come.  If you are a people watcher - so it is also a fun time to just sip a beer and watch people walk by.  Winter is also the time of year when the sea is calmer and so perhaps better for scuba diving, snorkeling and swimming in the sea.

In truth, there is no bad time to visit the Phuket area - do your research and you'll not likely be disappointed.