From
www.phuket.com:
The weather in Phuket in November shows the clear signs of the rainy low season coming to an end and the sunny high season beginning. There are still around 14 days in the month which will be interrupted by one or two short but heavy showers dropping 298.3mm of rain, mostly at night. The reducing rainfall brings the temperatures up to 27.5°C (81.5°F) and, while the humidity starts to creep down, the 73% average will still feel quite sticky. Gentle breezes are mostly blowing out of the east, resulting in calmer seas at around 29°C (84°F) – perfect for Loy Krathong as well as for diving and snorkelling.
Read more at:
http://www.phuket.com/island/weather-november.htm?cid=ch:OTH:001
The weather in Phuket in December is almost exclusively warm and sunny as the high season begins in earnest, with only a few last signs of the rainy season which preceded it. Rainfall is back down to a mere 50.8mm and only about eight in the month experiencing relatively light showers, mostly at night. With so little rain, humidity also drops sharply to just 68%. Gentle breezes from the east cool down the 27.6°C (81.7°F) temperatures without ruffling the calm 28°C (82°F) seas. As this marks the beginning of the high season, expect crowds at the major attractions and hotel and flight prices to begin to rise, particularly in the run-up to New Year.
Read more at:
http://www.phuket.com/island/weather-december.htm?cid=ch:OTH:001