If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Chumphon: The hottest months are usually April and May, with an average temperature of 28°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Chumphon are October, September, July and November, with each month seeing an average of 220 mm of rainfall.