It is important to understand the dynamical processes that cause heat waves at regional scales. This study examined the physical mechanism that was responsible for a heat wave in South Korea in August 2016. Unlike previous August heat waves over the Korean Peninsula, the intensity of the geopotential height over the Kamchatka Peninsula in August 2016 was the strongest since 1979, which acted as an atmospheric blocking in the downstream region of the Korean Peninsula. Therefore, the anomalous high geopotential height in Mongolia, where the surface temperature was quite high, was observed persistently in August 2016. This anomalous high in Mongolia induced northerly winds with warm temperatures onto the Korean Peninsula, which contributed to a heat wave in August 2016. We further showed that the anomalous high geopotential height over the Kamchatka Peninsula in August 2016 was triggered by strong convection in the western-to-central subtropical Pacific through atmospheric teleconnections, which was quite different from a typical heat wave over the Korean Peninsula, in which convective forcing around the South China Sea is strong. This implies that convective forcing in the subtropical Pacific should also be monitored to predict heat wave events in East Asia, including South Korea. On the other hand, the zonal wave train associated with the circumglobal teleconnection pattern is also associated with the anomalous high geopotential height around Mongolia and the Kamchatka Peninsula, which may have contributed to the heat wave in August 2016.

Several climate factors were identified that affect the surface air temperature (SAT) variations in Korea during summer (June‐July‐August). Korean summer SAT variation exhibits remarkable differences between early summer (June) and late summer (July and August). On one hand, the significant warming trend during early summer is primarily influenced by the global‐scale trend that is manifested in East Asia. The residual variability, obtained by removing warming trend from total SAT, represents Korean SAT variability independent of the global‐scale trend. This residual variability is closely related to the meridional dipole‐like air temperature structure between Korea and northeastern China, which is largely controlled by the atmospheric circulations over East Asia. However, this atmospheric structure does not originate from the remote oceanic forcing such as sea surface temperature (SST) variability over Pacific. During late summer, on the other hand, the Korean SAT is dominantly regulated by the atmospheric variability, which is closely related to the Pacific SST variability, while the contribution of global warming signal is insignificant. The SST anomalies in the central to eastern tropical Pacific lead to a dipole‐like atmospheric circulation from the tropics to East Asia, which modulates SAT in Korea. These results imply that the Korean SAT variability during early and late summer has different sources. That is, both the global‐scale trend and atmospheric variability over the East Asia should be considered in monitoring Korean SAT during early summer, whereas the SST variability in the central to eastern tropical Pacific needs more attention during late summer.