We observe a notable decreasing trend of June rainfall over the Korean peninsula in recent 20 years. This drought condition is found to be linked to the polarizing trend of rainfall intensity; more non‐rain and drizzle‐like rain, less moderate‐intensity rain, and more heavy rain events. Overall, the June drought over the Korean peninsula is found to be associated with less occurring moderate‐intensity rain. This feature is interpreted as that the dominant warm‐type heavy rain systems with a medium storm height tends to be less frequent while cold‐type heavy rains characterized by taller storm become more frequent during last 20 years. The northwestward expansion of the North Pacific high in June appears to weaken the continuous moisture supply to the Korean peninsula, which is a main element of forming the warm‐type heavy rain there. Climatological mean (left) and linear trend (right) for the frequency distribution of storm height normalized by near‐surface radar reflectivities over the Korean domain (June 1998–2017).