Seoul Records Hottest May Since 1907
In 1907, Seoul experienced the hottest May on record, with parts of Gyeongbuk and Pohang narrowly avoiding tropical nights. Sea fog, a warming effect, and strong sunlight contributed to the temperature increase. “Humid weather is expected until tomorrow… Temperatures will return to normal from Friday.”
On the 21st, during the summer solar term known as “Soman,” abundant sunlight contributes to the growth of all living things. On this day, the lowest temperature recorded in areas like Seoul, Incheon, parts of Gangwon, and Yeongnam was the highest for any May on record.
According to the Korea Meteorological Administration, as of 9:40 AM, areas including Seoul and Incheon, along with parts of Gangwon and Yeongnam, reported the highest minimum temperatures for May. In Seoul, the lowest temperature reached 23 degrees Celsius, surpassing the previous record set in 2018, which was an infamously hot year, with a minimum of 21.8 degrees.
A total of 11 areas broke their May record for the highest minimum temperature, with Gyeongbuk Pohang narrowly avoiding a tropical night by dropping from 25 degrees at 11:30 PM to 23.8 degrees by the following morning. Tropical nights occur when temperatures remain above 25 degrees from 6:00 PM to 9:00 AM the next day.
This May heatwave was due to warm, humid winds and thick fog, coupled with the warming effect known as the “Föhn Effect,” as analyzed by the Korea Meteorological Administration. A mobile high-pressure system to the east of Japan brought moisture-laden warm southerly winds to Korea, causing temperatures to rise 2 to 7 degrees above the seasonal norms (10-15 degrees for lows and 22-27 degrees for highs). For May 21, the morning low was forecasted between 13 and 21 degrees, and afternoon highs were expected to reach 17 to 28 degrees.
However, sea surface temperatures around the coastal regions were cooler, resulting in thick fog with visibility down to under 200 meters, primarily along the western and southern coasts. During the day, intense sunlight heated the ground, but fog and clouds trapped the heat in the atmosphere, exacerbating temperature rises.
Additionally, areas where winds encountered mountain ranges experienced the “Föhn Effect,” which contributes to the hot and humid weather. This effect occurs when winds travel over mountain peaks and down slopes, becoming warm and dry. As a result, the previous day’s maximum temperatures soared to 33.9 degrees in Uljin, Gyeongbuk, and 33.7 degrees in Daegu.
The Korea Meteorological Administration advises that temperatures will remain higher than normal until the next day. A spokesman added, “Tomorrow, southerly winds will sweep into our country due to a trough coming down from the north, keeping temperatures high until they revert to average levels by Friday.”
The trough is also expected to bring rain through the night and into the 22nd. Predicted rainfall tonight is between 5-30mm for eastern Gyeonggi, 5-40mm for Gangwon, and 5-40mm across Chungcheong, Jeolla, and Gyeongsang regions.