South Korea's average high temperature rose to 28 C last month, making it the hottest June on record since authorities began collecting relevant data in 1973, a government agency said Friday.

The Korea Meteorological Administration (KMA) said June's average high temperature was also 1.5 C higher than the average of the past 30 years, noting the extraordinarily hot weather was caused by North Pacific high pressure and the influx of warm southwesterly winds.

Last month's average temperature was tallied at 22.8 C, 1.6 C higher than the 30-year average, the KMA said.

Last month's number of heat wave days also increased to 2 days, the highest figure for June, while the month's average low temperature was 18.4 C, the second highest after 18.6 C recorded in 2013, it said.

"From the beginning of June, hot air settled in the upper and lower atmosphere. The North Pacific high pressure, which is high in temperature and humidity, exerted influence, and in the west, warm southwesterly winds flowed into the atmosphere. In addition, strong solar radiation added to the nationwide heat wave," a KMA official said.

Notably, Seoul's daytime high soared to 35.4 C on June 22, the fifth-highest temperature on record for late June, while the temperature soared to 36.3 C in Chuncheon in Gangwon Province on the same day.

The KMA also said rain frequently fell, particularly in the southern regions last month, as low pressure approached periodically. June's precipitation reached 215.5 millimeters in southern regions, 313.8 mm on Jeju Island and 142.4 mm in central regions, it added. (Yonhap)