Heat above 40 degrees Celsius, severe drought and record downpours. Extreme weather events came in rapid succession this summer and regional disparities widened, raising the risk of what forecasters call compound disasters.
The nationwide average temperature from June through August was 25.4 degrees Celsius, 1.7 degrees above the long-term norm, according to the 2026 Summer Climate Report released by the Korea Meteorological Administration on the 3rd. That ranks third since 1973, when the national observation network was expanded, behind last year's 25.7 degrees and 25.6 degrees in 2024. The past three summers now hold the top three spots on record.
From mid-July, the country came under the simultaneous influence of the North Pacific high and the Tibetan high, keeping temperatures elevated day and night. From late July into early August, strong westerly winds combined with terrain effects concentrated the heat in the South Gyeongsang region. Yangsan hit a daily high of 42.5 degrees on Aug. 2, the highest ever recorded there.
Days with a daily high of 39 degrees or more — one of the thresholds for a severe heat wave alert — occurred 42 times, the most since 2010. The nationwide average temperature in the first 10 days of August was 29.1 degrees, a record for that period.
The nationwide average number of heat wave days reached 21.5, more than double the norm of 10.6. In parts of North Chungcheong and the Jeolla provinces and in inland Gyeongsang areas, heat wave days topped 30. Nights brought little relief. Tropical nights totaled 18.2 days, the second-most on record after 2024. Eleven observation points including Gwangju, Namwon, Wando and Gumi logged their highest number of tropical nights since records began.
Rainfall, meanwhile, fell short of normal levels. Nationwide precipitation totaled 558.6 millimeters this summer, or 76.1% of the norm of 727.3 millimeters. There were 31.2 days with rain, 7.3 fewer than the norm.
The rainy season began late, delayed by atmospheric blocking and the slower expansion of the North Pacific high. Jeju and southern regions entered the season on June 30 and central regions on July 1, arriving 11, 7 and 6 days later than usual. The stationary front then moved quickly north into North Korea, leaving nationwide rainy-season precipitation at 218.6 millimeters, or 60.3% of the norm.
Regional gaps in rainfall were wide. Heavy rain fell on central regions where the stationary front settled, while the south endured heat and drought — a stark split. South Gyeongsang recorded 48.2 days of meteorological drought this summer, the most of any region.
By the second half of August, however, a low-pressure system brought record downpours to South Gyeongsang. Geoje received 968.1 millimeters of rain over four days from the 15th to the 18th, equivalent to half of the city's annual precipitation. Heavy rain also hit the Chungcheong and Jeolla regions on the 30th and 31st of last month as another stationary front moved in. Boseong and Yeonggwang in South Jeolla saw rainfall exceeding 100 millimeters an hour.
The waters around the Korean Peninsula were also unusually warm. The average sea surface temperature in surrounding waters was 24.3 degrees this summer, the highest in the past decade. The South Sea was warmest at 25.4 degrees, followed by the East Sea at 24.2 degrees and the West Sea at 23.2 degrees.
"Climate variability has increased, and the risks of regional polarization and compound disasters have become clear," said Lee Mi-sun, administrator of the Korea Meteorological Administration. "We will work closely with disaster response agencies to strengthen preparedness for climate disasters."
