Marigold flowers are in full bloom under the clear autumn sky at Everland in Yongin, 60 km south of Seoul, on Monday. (Yonhap)

Temperatures took a sudden dive across the country Tuesday, prompting people to change from summer clothes to autumn clothes.

According to the Korea Meteorological Administration (KMA), the mercury dropped by eight to 13 C from the previous day, as cold air moved here from the north.

Tuesday's morning lows ranged from 11-19 C, 2-4 C lower than the 30-year average and 8-13 C lower than the day before, the KMA noted.

As of 7 a.m., temperatures had hit 16.2 C in Seoul, 15.5 C in Incheon, 15.9 C in Daejeon, 17.4 C in Gwangju and 18.2 C in Busan, it said, adding the daily highs will reach 19-25 C.

People nationwide were caught off guard by the sudden steep fall in temperatures, as a heat wave advisory was in effect in some southern regions only until two days ago.

The weather has changed so much in a matter of several days that people now worry about frost in the mountains instead of unseasonal autumn heat, KMA officials said.

The chilly weather is expected to continue Wednesday, as the morning low in Gangwon Province, east of Seoul, will fall below 5 C, and the first frost of the season could occur in high-altitude areas, they said. (Yonhap)