Weather will likely play an important role when you plan your trip to Uljin, 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 22°C, while the coldest months are January and February, with an average of 4°C. The rainiest months in Uljin are August, July, September and October, with each month seeing an average of 207 mm of rainfall.