Weather is probably a major factor when you plan your trip to Sanyang-eup, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July, with an average temperature of 23°C, while the coldest months are January and February, with an average of 6°C. The rainiest months in Sanyang-eup are July, August, September and June, with each month seeing an average of 238 mm of rainfall.