South Korea has experienced a sharp rise in extreme heat over the past 113 years, with the number of heat‑wave days doubling and tropical nights increasing more than fourfold.

According to the Korea Meteorological Administration’s climate change report released Tuesday, average annual heat wave days rose from seven‑point‑seven days in the 1910s to 16‑point‑nine days in the 2020s. The report covered the period from 1912 to 2024.

Tropical nights, defined as when nighttime temperatures remain at or above 25 degrees Celsius, increased from six‑point‑seven days to 28 days over the same period.

Regionally, heat waves were concentrated mainly in inland North Gyeongsang Province in the 1970s but have shown a clear nationwide increase since the 2010s.

Tropical nights, once largely limited to parts of the southern coast and Jeju Island in the 1970s and 1980s, expanded westward in the 2010s and surged across most regions in the 2020s.

The report also found that the national annual average temperature has risen by zero‑point‑21 degrees Celsius per decade, climbing from 12 degrees in the 1910s to 13‑point‑nine degrees in the 2010s and further to 14‑point‑eight degrees in the 2020s.