South Korea has been rocked by volatile weather dubbed a “Goblin Monsoon" by local media, with heavy rain and heat waves alternating in a short period of time over recent weeks. This is due to the effects of low pressure that create unpredictable rain clouds, but is not a new phenomenon, the weather agency said Tuesday.

Over the last few weeks, rain clouds have come and gone nationwide, moving away quickly after raining over small areas. These rainy periods are then followed by heat waves.

“People usually expect continuous rainy days when the monsoon season comes. But in fact, in the early stage of the monsoon period, it is common for heat waves and heavy rains to take turns ... due to the effect of low pressure which intervenes before a full-fledged stationary front takes place," Woo Jin-kyun, an official at the Korea Meteorological Administration, told the The Korea Herald.

Unlike stationary fronts, which are usually generated in the shape of a long horizontal string, the rainy fronts generated by low pressure are vertical and relatively short. “The vertical front moves from west to east, causing heavy rains in small regions over a short period of time, and when the front moves away with the cloud coverage, the hot weather resumes,” explained Woo.

Woo also noted that it is too early to say whether the recent volatile weather is a result of climate change.

Residents of Guro-gu, southwestern Seoul, received the first downpour alert text message from the KMA as "extreme heavy rain" fell in the region Tuesday afternoon, amid heavy rain across the country.

"Extreme heavy rain" refers to cases that meet both the criteria of "50 millimeters of rain in an hour" and "90 mm of rain in three hours." The message sent Tuesday is the first downpour alert message sent by the KMA since the start of the summer, when the agency launched a pilot project to send alert messages to citizens in cases of extreme downpour in the Seoul metropolitan area.

Heavy downpour affected traffic, causing damage to facilities across the country. Trains on the Gyeongbu Line, including Seoul Subway Line 1, were suspended for 16 minutes from 3:56 p.m. to 4:12 p.m. In Yeoju, Gyeonggi Province, a man in his 70s who was walking along the river was washed away by high waters and found dead at around 1:30 p.m. Meanwhile, the ceiling of a day care center in Buk-gu, Gwangju, collapsed due to the rain, but no casualties were reported.

The KMA said that rain will continue throughout the country from Tuesday to Wednesday, and the stationary front will move northward to the central region from Wednesday night, increasing the possibility of heavy rain until early next week.

Until Wednesday morning, a collection of small but strong rain clouds will enter from the West Sea. The KMA urged citizens to take precautions as a downpour of 30 to 70 millimeters per hour is expected throughout the country, combined with gusts of wind, thunder and lightning.

The Seoul metropolitan area, inland Gangwon Province, Chungcheong Province, Jeolla Province and inland Northern Gyeongsang Province are expected to see 50 to 120 mm of rain until Wednesday. The southern part of Chungcheong Province and North Jeolla Province might see more than 200 mm of rain, the weather agency warned.

As of 4 p.m. Tuesday, heavy rain advisories have been issued in most parts of the Seoul metropolitan area, inland Gangwon Province, Gyeongsang Province and Jeolla Province.

The KMA added that rain from Tuesday to Wednesday is due to a collection of small clouds and thunderstorms, which makes it difficult to forecast the exact weather patterns. "There will be large differences in precipitation even among nearby regions. Please check real-time forecasts for more accurate information," said Park Jeong-min, a KMA weather analyst during a briefing on Tuesday.