If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Hwaseong: The hottest months are usually August and July, with an average temperature of 24°C, while the coldest months are January and December, with an average of 1°C. The rainiest months in Hwaseong are July, August, September and June, with each month seeing an average of 224 mm of rainfall.