The best months to visit South Korea are October and April. See monthly temperatures, rainfall and rain days (1991–2020 averages) to plan your trip.
Average daytime high and monthly rainfall in South Korea: January 3°C / 19mm; February 7°C / 26mm; March 11°C / 38mm; April 21°C / 69mm; May 24°C / 96mm; June 29°C / 127mm; July 29°C / 318mm; August 32°C / 265mm; September 28°C / 124mm; October 20°C / 54mm; November 13°C / 47mm; December 4°C / 23mm.