Three women in their 80s were found dead of heatstroke Saturday while working in the farm fields in the central and southern parts of the country. The daytime temperatures of the concerned regions recorded over 33 degrees Celsius. The regions were issued with a heat wave advisory, health authorities said.

The death toll has climbed to seven since last week as temperatures across the nation continue to soar.

Most of the victims killed by heatstroke were elderly, working on farms in the countryside, officials said.

One of the victims was a 34-year-old construction worker in South Chungcheong Province, health authorities added.

On Saturday, the temperature of Yeongcheon in North Gyeongsang Province reached 37.5 degrees Celsius, the highest recorded temperature that day. Other regions in South Gyeongsang Province, South Jeolla Province and Gangwon Province also recorded around 35 degrees Celsius. 

A heat wave advisory was issued in the southern city of Daegu, and some cities in North Gyeongsang and Chungcheong provinces. The authorities issue a heat wave advisory when the highest temperature of the day reaches over 33 degrees Celsius for more than two days.

The tropical night phenomenon also occurred in Daegu for six days and on Jejudo Island for 10 days, as the lowest night temperature remained over 25 degrees Celsius.

The weather agency said the heat wave will likely continue until Aug. 10.

Korea Centers for Disease Control and Prevention advised the elderly to drink water frequently and restrain from outdoor activities in the daytime in order to prevent heatstroke.

As temperatures soar, people have flocked to the coastal areas to cool down over the weekend.

Haeundae Beach and other sites in Busan attracted about 2.6 million people, while other beaches around the East Sea, such as Sokcho Beach in Gangwon Province, drew more than 1.7 million, officials said.

More than five drownings were also reported over the weekend, including a 12-year-old victim in South Gyeongsang Province.

On Sunday, the major highways showed heavy traffic as people returned home to Seoul. Over 410,000 cars entered Seoul, mostly through the Gyeongbu Highway that links the capital to Busan and Yeongdong Highway that connects the capital to Gangwon Province, transport officials said.

By Lee Hyun-jeong (rene@heraldcorp.com)