Rain and hail are forecast for central regions and North Jeolla and Gyeongsang provinces on Saturday.
Expected rainfall is five to 70 millimeters with some areas seeing torrential showers of over 30 millimeters per hour.
People camping near valleys and streams are advised to take precautions against rising water levels.
Rain will continue in the central regions through Sunday morning while inland areas will see sporadic showers into the afternoon with the expected volume ranging from five to 60 millimeters.
Sunday morning lows will be similar to Saturday ranging from 17 to 20 degrees Celsius with 19 degrees forecast in Seoul.
Daytime highs will be similar or slightly lower at 22 to 29 degrees nationwide with the mercury reaching 27 degrees in the capital.