South Korea has a temperate climate, with four distinct seasons. Winters are cold and windy, and snow falls in all but the southernmost regions. Summers are hot, humid, and rainy. The weather in South Korea is affected by the Asian continent and the surrounding seas. The Asian monsoon (large-scale wind systems that reverse direction seasonally) brings frigid air from the Arctic in winter and warm, moisture-laden air from the South China Sea in summer.

In Seoul the average January temperature range is -7° to 1°C (19° to 33°F), and the average July temperature range is 22° to 29°C (71° to 83°F). Winter temperatures are higher along the southern coast and considerably lower in the mountainous interior.

The average annual precipitation in Seoul is 1,370 mm (54 in), and in Busan it is 1,470 mm (58 in). Rainfall is concentrated in the summer months (June to September). The southern coast is subject to late summer typhoons that bring strong winds and heavy rains.