My fiancé and I are thinking about going to Thailand (beach trip) for our honeymoon next September. We are wondering if this will be a waste of money since it will be rainy season. Please help!
No - often the weather is still hot and sunny during September - especially in the Gulf of Thailand. It's quite possible that visiting Koh Tao, Phangan or Samui during September you'll get to enjoy flat seas and good weather.
The rain tends to be further north at that time, and it's not till November that the Gulf enters it's monsoon rainfall season.
[Refer to any decent climate chart for the southern Gulf of Thailand - i.e. http://thailandforvisitors.com/south/samui/sam-weather.html] over 6 years ago