Planning for the weather is a good way to make your trip to Suwon relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July with an average temp of 74°F, while the coldest months are January and December with an average of 34°F. The rainiest months in Suwon are July, August, September, and June, with each month seeing an average of 9 inches of rainfall.