Seoul, Aug 3 (IANS): The scorching heat wave gripping South Korea for over one week is expected to further intensify on Thursday, the state weather agency said, with the highest temperatures climbing from 33 to 38 degrees Celsius across the nation.

The Korea Meteorological Administration (KMA) said the hot and humid North Pacific high pressure has completely covered the nation, pushing up the maximum sensible temperatures above 35 degrees in most regions in the day, reports Yonhap News Agency.

Daytime highs are to reach 35 degrees in Seoul, Ulsan and Daejeon, 33 degrees in Incheon, 36 degrees in Daegu and Gwangju and 34 degrees in Busan, the KMA said, adding their apparent temperatures will be a few degrees higher.

The midday ultraviolet index will also rise to a very high level in most regions, the KMA said, asking people to stay indoors or in the shade.

The tropical night phenomenon is expected to continue in urban and coastal areas, in particular, it said.

Gangneung, an east coastal city, experienced the super tropical night on Wednesday, with its nighttime low staying above 30 degrees, the agency said.

Due to atmospheric instability, there will be occasional showers across the country, with precipitation reaching up to 30 mm per hour, the KMA said.

Meanwhile, the death toll from the heat wave has increased to 23, more than tripling from last year, as the government's heat warning remained at the highest level of "serious".