Korea's nationwide average temperature reached 22.2 degrees Celsius last month, the seventh-highest since 1973. However, the number of heatwave days stood at 0.6, roughly the average level, and no tropical nights occurred. The rainy season arrived later than usual due to the development of atmospheric blocking and a delayed expansion of the North Pacific high-pressure system.
According to the "June 2026 Climate Characteristics" released Friday by the Korea Meteorological Administration (KMA), the nationwide average temperature in June was 22.2 degrees, ranking seventh in history (1973-2026). It was 0.8 degrees higher than the average of 21.4 degrees, but 0.7 degrees lower than last year's 22.9 degrees, the hottest on record.
Temperatures rose sharply in early and mid-June. From June 1 to 4, Typhoon Jangmi moved northward toward the seas south of Japan, drawing in hot and humid air that pushed temperatures up significantly. From the 13th, warm air flowed in from the edge of a high-pressure system.
The nationwide number of heatwave days stood at 0.6, near the average of 0.7. This contrasts with June 2024 (2.8 days) and last year (2.0 days), which recorded the first- and second-highest June heatwave days in history. No tropical nights occurred nationwide. In Seoul, June tropical nights, which had occurred for four consecutive years since 2022, disappeared this year.
Precipitation stood at 95.4 millimeters, only 64.9% of the average of 148.2 millimeters, and less than half of last year's 184.7 millimeters. The number of precipitation days was also 6.9, three fewer than the average of 9.9 days, ranking as the third-lowest in history. Although rainfall was scarce, there was one bout of concentrated precipitation. Heavy rain fell nationwide from the 19th to the 20th, with 64.4% of June's precipitation concentrated during this period.
The rainy season was also late. The rainy season refers to the period when a stationary front lingers near Korea and brings heavy rain. Even if the rainy season starts late or is shortened, localized torrential downpours can follow afterward.
This rainy season began June 30 on Jeju Island and in the southern region, 11 days and 7 days later than usual, respectively. The central region's rainy season began July 1. Analysts attribute this to suppressed convective activity in the tropical western Pacific, along with the northward movement of typhoons Mekkhala and Higos, which pushed the edge of the North Pacific high-pressure system eastward and delayed its northwestward expansion. Due to the rainy season front, heavy rain is forecast nationwide from July 5.
"Last year, heatwaves and tropical nights occurred frequently starting in June and the rainy season began early, whereas this June, heatwaves occurred at the average level and the rainy season was delayed," KMA Administrator Lee Mi-seon said. She added, "As climate variability is increasing, we will closely monitor abnormal weather phenomena and cooperate with disaster-prevention agencies to prepare for hazardous weather."
As the full-fledged rainy season began, President Lee Jae-myung on Wednesday urged local governments to thoroughly prepare in advance, saying, "The July rainy season is unusual, and extreme downpours such as monster rains are also a concern." President Lee asked for preemptive inspections of vulnerable facilities such as landslide-prone areas, semi-basement housing, aging facilities, construction sites, and stormwater drains.
