Originally Posted by RustyC

May is normally the hottest month. Though the thing working most in your favor in Phuket or just about anywhere in Thailand is the military government's crackdown on beach vendors. Before they took over you'd have popular beaches heavily encroached by umbrella/chair vendors, with too many boats parked and too many vendors of all types. Now the numbers are greatly reduced, there's noticeably more space and in some places there's a mandatory day off with no umbrellas and chairs.

Don't even think of renting a jet ski. Scams in that area have been incredibly persistent.

Beach chasers long ago decided Phuket was too built out and started going to Ko Lanta, Ko Chang (also very developed now), Ko Samui (almost like Phuket), and lately further afield in Trang province. Having been to the postcard places and seeing them get more crowded, I tend to save the beaches for other countries. I liked the Perhentians a lot in Malaysia, But once you've been to the Seychelles it's hard to see other places the same.

The advice about the currents for that time of year is also true. Don't assume too much about ability to do boat trips.

You can still have a fine time, though, especially if it's your first trip.