Rainfall reaching up to 250 millimeters will fall nationwide from Friday afternoon, bringing an end to the prolonged summer weather in South Korea, said the Korea Meteorological Administration on Thursday.

The atmosphere above the Korean Peninsula was covered by the Tibetan and North Pacific high-pressure systems, resulting in unprecedented heat waves and tropical nights during Chuseok, Korea’s traditional mid-autumn festival to wish for a good harvest.

According to the KMA, the continued hot and humid weather seems to be nearing its end, as the national weather agency anticipates cold air to move in after Friday afternoon.

“As the high-pressure systems weaken, cold air that has been trapped in the northwest will descend into Korea, allowing temperatures to cool,” said KMA official Gong Sang-min during Thursday’s press briefing.

However, Gong added that the cold air will “collide” with preexisting warm air that has been lingering above the atmosphere, leading to heavy rain nationwide -- focused especially in the central region, referring to the Greater Seoul area, Gangwon Province and the Chungcheong Provinces.

“(The KMA) currently anticipates heavy rain to fall from Friday afternoon until Saturday morning, with rainfall ranging between 30 to 50 millimeters per hour focused on the central region,” added Gong. Rainfall of up to 30 mm per hour will also fall in the Jeolla Provinces and the Gyeongsang Provinces over the same period.

The state weather agency added that rain clouds will then expand to the southern parts of Korea from Saturday morning, as heavily hit regions in Jeju Island and Busan can expect to see rainfall from Friday until Sunday ranging in total up to 250 mm and 150 mm, respectively.

As the cold air moves in over the Korean Peninsula, temperatures will no longer surpass 30 degrees Celsius from Friday, according to the KMA. While average daytime temperatures are expected to reach up to 29 C on Friday, on Saturday and Sunday, the KMA anticipates average daytime temperatures to reach 23 C and 25 C, respectively.

According to the 10-day forecast from Thursday until Sept. 29, daytime temperatures are expected to range between 21 C to 29 C, though such numbers are subject to change depending on the conditions.

Although temperatures will cool down from Friday compared to the past few weeks, the KMA added that temperatures will be 2 C to 3 C warmer than in previous years, resulting in a warmer fall compared to the past.