Planning for the weather is a good way to make your trip to Rach Gia relaxing and enjoyable, especially when you’re splurging. The hottest months are usually March and April, with an average temperature of 29°C, while the coldest months are January and December, with an average of 27°C. The rainiest months in Rach Gia are September, October, July and May, with each month seeing an average of 366 mm of rainfall.