This study analysed data on the weather of Seoul, Gwangju and Mokpo to examine the degree of temperature increase in those Korean cities. 1) When the results of the analysis were compared with those of previously analysed temperature increase in 1990s and 1940s, there was an increase in temperature of $1.7^{circ}C$ in Seoul, $1.5^{circ}C$ in Gwangju and $0.7^{circ}C$ in Mokpo. 2) According to the seasonal analysis, $1.7^{circ}C$ in Seoul, $1.5^{circ}C$ in Gwangju and $0.7^{circ}C$ in Mokpo increased in Spring. On a monthly basis in Spring increase in April was highest($2.3^{circ}C$ and $1.0^{circ}C$ in Gwangju and Mokpo, respectively). As for Seoul, $2.4^{circ}C$ increased in March, highest. In July and August of Summer, no significant change occurred in the three cities, but in Autumn, $1.0^{circ}C,;1.5^{circ}C$, and $0.3^{circ}C$ in Seoul, Gwangju and Mokpo increased, respectively. In Winter, $2.9^{circ}C$ in Seoul, $1.9^{circ}C$ in Gwangju, and $2.3^{circ}C$ in Mokpo increased, respectively.