Planning for the weather is a good way to make your trip to Ratchaburi relaxing and enjoyable, especially when you’re splurging. The hottest months are usually April and May, with an average temperature of 30°C, while the coldest months are December and January, with an average of 27°C. The rainiest months in Ratchaburi are September, October, May and August, with each month seeing an average of 185 mm of rainfall.