People walk amid a heat haze forming above the streets in Yeouido, western Seoul, Monday. (Yonhap)

Summer is right around the corner, with average daytime temperatures nationwide estimated to record over 30 degrees Celsius throughout the week, according to the Korea Meteorological Administration on Monday.

Monday’s average daytime temperatures nationwide were to range between 26 C and 33 C, as South Korea falls under the influence of high pressure coming toward the peninsula from Mongolia while warm air comes in from the west, according to the KMA.

On Tuesday and Wednesday, morning temperatures are expected to range between 17 C and 23 C, with daytime temperatures to range between 27 C and 33 C.

The current forecast is 3 degrees higher than in previous years, the KMA added.

In Seoul, Monday’s daytime high temperatures were expected to reach up to 30 C, while cities such as Daegu and Gumi, North Gyeongsang Province, can expect to see daytime high temperatures as high as 33 C.

The state weather agency defines the start of summer as the day when the average daily temperature reaches over 20 C and does not fall below it for nine days. The KMA forecasts average temperatures in most parts of Korea to top 30 C by June 19.

However, due to high humidity levels the KMA stated that it would feel much hotter than the actual temperature for the next nine days.

Until June 19, the KMA estimates it to feel like 31 C or higher, based on the air temperature combined with relative humidity and wind speed.

Pedestrians walk with parasols for shade in Gyeongsan, North Gyeongsang Province, Monday. (Yonhap)

As of 10 a.m. on Monday, the first heat wave warnings of the year were also issued in the southeastern region, including Daegu, Ulsan and Gyeongju, North Gyeongsang Province. Heat wave warnings in Korea are issued when the highest apparent temperature is expected to reach 35 C or higher.

In 2023, the first heat wave warnings were issued on June 17, meaning this year’s heat wave warnings have arrived a week earlier than the previous year.

Meanwhile, summer in Korea this year is expected to be hotter than usual, according to the KMA’s prediction report for June to August. While there is a 50 percent chance for temperatures in June and August to exceed the previous three-decade average, there is a 40 percent chance for temperatures to surpass average temperatures in July.