Unpredictable Spring Weather... Hot Spells, Cold Waves, and Rain Every Third Day

KMA 'Spring Climate Analysis': Above-Normal Temperatures in March, Heatwaves and Cold Snaps in April
Snow and Frequent Rain in May... Highest Number of Rainy Days Recorded for May
Cold Air Moving South, Stagnant Airflow Causes Cool Weather and Frequent Rain

[Asia Economy Reporter Han Jinju] This spring saw alternating early summer temperatures and cold waves, with rain falling approximately once every three days.

On the 8th, the Korea Meteorological Administration announced the '2021 Spring Climate Analysis Results,' stating that due to unusually high temperatures in March, cherry blossoms in Seoul bloomed the earliest since 1922, and March temperatures were the highest since 1973. In April, cold waves and early summer weather appeared simultaneously, and from mid-April onward, cloudy and cool weather continued. The average temperature in May was 16.6°C, the lowest since 1995 (16°C), and the highest temperature was the fourth lowest on record.

Low-pressure systems developing in the west periodically approached the Korean Peninsula, resulting in the seventh highest spring precipitation since 1973. March saw the most rain and snow during spring, with snow accumulating in the Yeongdong region of Gangwon Province, causing vehicle isolation and structural collapses. In April, cold waves and early summer weather appeared simultaneously.

In May, cold and dry air descended from the upper atmosphere, causing rain approximately every two days. The number of rainy days in May was 14.5, 1.7 times the average (8.7 days), marking the highest number of rainy days in May on record. The highest temperature in May was the fourth lowest on record. The atmosphere became unstable, resulting in frequent hail (0.6 days) and lightning, and snow even fell in the mountainous areas of Gangwon.

The reason for the high temperatures and heavy rainfall until mid-March to mid-April was that Arctic temperatures were lower than average, forming a positive Arctic Oscillation and jet stream at high latitudes, which trapped cold Arctic air and weakened the Siberian High. Due to La Ni?a, sea surface temperatures in the tropical western Pacific remained high, promoting active upward air currents, while descending air currents developed around Korea, contributing to the development of migratory high and low-pressure systems.

The cool weather after mid-April was caused by a temporary rise in Arctic temperatures, weakening the jet stream, and warm air masses stagnating near the Ural Mountains, allowing cold and dry air to descend to mid-latitudes. Compared to the average, the North Pacific High expanded, and moisture flowing along its edges collided with cold upper-level air from the north, intensifying atmospheric instability and increasing precipitation.

Park Kwang-seok, head of the Korea Meteorological Administration, said, "Last spring began with a sudden heavy snowfall in Gangwon Yeongdong on Samiljeol (March 1), followed by abnormal high temperatures in March, cold waves in April, and low temperatures in May, showing significant seasonal variability." He added, "We will do our best to diagnose the causes of abnormal climate and promptly deliver rapidly changing weather conditions to provide useful information to the public."

This content was produced with the assistance of AI translation services.