Cooler late June, delayed monsoon: Is Korea’s summer just warming up?

Summer is in full swing in South Korea, but it doesn’t feel like the late June most Koreans have come to expect.

While temperatures are forecast to climb to 33 degrees Celsius in Seoul on Monday and exceed 30 degrees across much of the country’s inland areas, according to the Korea Meteorological Administration, the muggy air that usually blankets the country this time of year has yet to take hold due to the delayed monsoon.

Last year, the monsoon began on Jeju Island on June 12, reached the country’s central and southern regions on June 19, and lasted until mid-July.

This year, however, the seasonal rain front has yet to form, with only scattered showers falling in place of prolonged monsoon rainfall.

Between 5 and 40 millimeters of rain is expected later Monday across the capital region, the mountainous areas of Gangwon Province and the Chungcheong region, the weather agency said.

The conditions have brought a much cooler June than last year.

On Monday a year earlier, Gyeongju in North Gyeongsang Province recorded the nation’s highest daytime temperature of 37.5 degrees. Highs also reached 36.1 degrees in Daegu, 35.1 degrees in Pohang and 34 degrees in Andong.

The country’s weather pattern stands in sharp contrast to that of Europe, where record-breaking heat has gripped France, Germany, the United Kingdom and other countries, triggering widespread power outages, school closures and reduced business hours.

France, for example, recorded a nationwide average temperature of 30 degrees on Wednesday, marking its hottest day since records began.

What has driven the record-breaking heat wave is a persistent high-pressure system over western and central Europe known as an omega block, a weather pattern that prevents the atmosphere from moving normally and allows heat to build up over the same area, news reports said.

The KMA attributed the unusual break from Korea’s typical early-summer heat and rainy season to cold, dry air from the north.

Late-June heat waves typically develop when the North Pacific High expands northward from south of Japan, bringing hot, humid air over the Korean Peninsula. But currently, the cold air of around minus 15 degrees in the upper atmosphere is keeping the system farther south, delaying the formation of the monsoon front.

Typhoons Mekkhala and Higos, now moving north toward Japan, have also helped delay the onset of the monsoon by limiting the northward expansion of the North Pacific High.

With the monsoon front still not fully formed, the KMA expects rain to begin on Jeju Island later this week before spreading to southern and inland parts of the country. Whether the rainfall will mark the official start of the monsoon remains uncertain.

July monsoon onsets have been rare since nationwide weather observations began in 1973. They have occurred only twice on Jeju Island, in 1982 and 2021, and just six times in the central region and five times in the southern region, officials said.

The monsoon typically begins on June 19 on Jeju Island, June 23 in the southern region and June 25 in the central region, based on the 1991–2020 average.

cjh@heraldcorp.com