Weather will likely play an important role when you plan your trip to Uljin, and keep 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 temp of 72°F, while the coldest months are January and February with an average of 39°F. The rainiest months in Uljin are August, July, September, and October, with each month seeing an average of 8 inches of rainfall.