Sweltering heat continues to grip the nation while the state weather agency said the record-breaking hot summer weather had been influenced by weather systems in northern China.

The Korea Meteorological Agency said Thursday that heated air that was created in northern China had risen to a high altitude and moved across southern Russia and the Korean Peninsula, before descending on South Korea. 

The migration happened at the same time as a high pressure system formed over South Korea, preventing the formation of clouds and exposing the country to more sunlight. 

On Friday, the KMA issued excessive heat warnings across the nation except some parts of Gangwon Province and North Gyeongsang Province.

Daytime highs reached 36 degrees Celsius in Seoul, 33 degrees Celsius in Daejeon, and 35 degrees Celsius in Gwangju and Daegu. 

This year is the first time a heat wave warning was issued in mid-May in any part of the country. A hot weather warning was issued for Gapyeong and Goyang of Gyeonggi Province on May 19.

Weather forecasters encouraged citizens to avoid outdoor activities and driving for long periods, warning that ozone concentrations were also high.

Ozone concentration levels were “bad” in metropolitan areas, southern Chungcheong Province, Jeolla Province and northern Gyeongsang Province.

On Thursday, the KMA issued a hot weather warning in Seoul, for the first time in this year. Thursday’s daytime high hit 35.1 degrees Celsius in Seoul. 

Daytime highs exceeded 35 degrees Celsius in other cities including Suwon, Daejeon and more.

A hot weather warning is issued when the daytime high reaches over 35 degrees Celsius and continued for two consecutive days. Hot weather advisories are issued when the daytime high is over 33 degrees Celsius. 

The KMA said that it expects to see sporadic rainfall over the weekend and on Monday, which would possibly reduce the temperature temporarily.

But the scorching heat wave that started in July will drag on till mid-September, it added.

By Kim Da-sol (ddd@heraldcorp.com)