South Korea woke up to the coldest autumn morning this year so far on Thursday due to cold air moving in from the north, with some areas seeing the mercury drop below zero, the national weather agency said.

The morning low in Seoul came to 10.2 degrees Celsius, down four degrees from the previous day’s 14.2 C, while the figure for Incheon, just 27 kilometers west of Seoul, plunged to 12.4 C as of Thursday at 8 a.m., according to the Korea Meteorological Administration.

The rapid temperature drop also hit other parts of the country. The 8 a.m. temperatures in Daejeon City recorded 13.3 C, 14.8 C in Gwangju, 14.6 C in Daegu, 14.3 in Ulsan and 16.3 C in Busan.

Temperatures on Mount Seorak in Gangwon Province plunged to minus 1.3 C in the morning, while the morning weather for Seolcheonbong in Muju County in North Jeolla Province dived to 0.4 C in the early morning.

The KMA forecast that across the country, daily high and low temperatures will fluctuate anywhere between 10 to 15 degrees.

The chillier autumn weather will likely continue over the weekend as strong winds are expected to sweep through most regions.

In particular, the lowest temperatures in the northern part of Gyeonggi Province, the mountainous areas of Gangwon Province and North Chungcheong Province are expected to plummet to 5 C or lower, which could cause a frost there.