ottest in 23 years, the Korea Meteorological Administration said on Tuesday.
The average daytime high from June to July this year soared to 29.1 degrees Celsius, making it the hottest summer since 1994 when it was slightly hotter at 29.9 degrees.
Temperatures this summer are higher than the annual average for the last 30 years, with Jeju Island whose average daytime high recorded 28 degrees, the hottest since 1973 when KMA began compiling relevant data.
The number of days affected by a heat wave with temperatures exceeding 33 degrees was already 7.5 days this summer, compared with 16.2 days in 1994 and 7.6 days in 1973.
"Instead of even levels of precipitation, this year's monsoon season brought unpredictable local downpours, making hot and humid conditions linger across the country," KMA said.
Temperatures hovering around 33 degrees are expected to last for a while nationwide, KMA said.
People shelter from the heat at Haeundae Beach in Busan on Tuesday. /Yonhap