Temperatures to near 30 C this weekend, with ozone caution in effect

Skies will be mostly clear across South Korea this weekend, with daytime temperatures rising to around 30 degrees Celsius. Strong sunshine is expected to push ozone concentrations higher, particularly in the Greater Seoul area.

Weather authorities said Friday that a mobile high-pressure system will dominate the Korean Peninsula through the weekend. With little cloud cover, intense sunlight will drive afternoon temperatures above 30 C across much of the inland regions.

On Saturday, morning lows are forecast between 13 and 20 C, with afternoon highs ranging from 23 to 32 C. Expected highs by city include Seoul at 32 C, Incheon at 30 C, Daejeon at 32 C, Gwangju at 31 C, Daegu at 29 C, Ulsan at 26 C and Busan at 27 C.

Sunday will bring slightly hotter conditions, with morning lows of 14 to 22 C and afternoon highs of 24 to 33 C. In some inland areas, added humidity could push the apparent temperature to around 31 C.

The apparent temperature factors in humidity alongside the actual air temperature. It generally matches the thermometer reading at 55 percent humidity, rising by roughly 1 C for every 10-percentage-point increase above that. People spending extended time outdoors during the midday heat should drink plenty of water and take regular breaks.

Ozone levels also warrant attention. Ozone forms when atmospheric pollutants such as volatile organic compounds react with strong sunlight. Elevated concentrations can irritate the eyes, skin and respiratory tract. Children, the elderly and those with respiratory conditions are advised to limit time outdoors during afternoon hours.

The National Institute of Environmental Research forecast that ozone levels in southern Gyeonggi Province will reach the "very bad" threshold on Saturday. The rest of the Greater Seoul area, along with Sejong, South Chungcheong, North Jeolla and South Jeolla provinces, are expected to register "bad" readings.

On Sunday, ozone concentrations in Seoul and Gyeonggi Province are forecast to reach "very bad" levels. Incheon, Sejong, North Chungcheong, South Chungcheong, North Jeolla, South Jeolla, Daegu, North Gyeongsang and South Gyeongsang are also expected to record "bad" readings.

Scattered showers of 5 to 20 millimeters are possible Sunday afternoon in northeastern Gyeonggi Province and the northern inland and mountain areas of Gangwon Province.

Coastal safety also requires attention. Swells are forecast to reach the shores of Jeju and the southern coast through Saturday morning. Waves may surge forcefully onto the shoreline or wash over rocky outcroppings and breakwaters, and people are advised to stay away from coastal areas where possible.