In this study, spatio-temporal distribution was analyzed with the number of days for summer heat wave and winter cold wave defined as three or more consecutive +5% quantile days and -5% quantile days, respectively, by using daily maximum temperature in summer and daily minimum temperature in winter during 1973-2015. Although monthly heat wave occurrence has been only concentrated in July and August during the 1970s and 1980s, it had further extended into June and September since the 2000s. Monthly cold spell occurrence has been distinguished by increasing occurrence ratio in the month of December since the 2000s. The occurrences of heat waves were classified into either strong or weak cluster depending on intensity and magnitude over the entire region of South Korea rather than in specific areas. On the other hand, the occurrences of cold spell were classified by intensity of cold spell and spatial distribution of dominant cold spell areas over South Korea.