A 'cooling fog' system, which is used to cool down citizens during the peak of summer, has already been activated in parts of South Korea.
And Daegu, a city known to be one of the hottest in the nation, is already feeling the summer heat.
I didn't think it was going to be hot since it's May. Now that I'm outside, it's hot. I'm quite worried about June, July and August."
In Seoul, temperatures have also risen sharply.
As the mercury soars past 30 degrees Celsius, the year's first heat wave advisory will be issued on Friday.
It marks just the second time that Seoul will be under a heat wave advisory in May, since May 2016.
Advisories are also being issued in other parts of the nation.
Temperatures are higher than the seasonal average due to a high pressure system from the North Pacific and high thermal pressure from China.
However, experts say this summer won't be as sweltering as last year, which was one of the hottest on record.
"During spring, Tibet was covered with snow, so the possibility of a strong and constant heat wave like last year is expected to be small.
The monsoon season is expected to arrive later than usual, with most of the summer rain to be concentrated in southern regions.
However, after monsoon season, bouts of heavy rain are expected across the country.
Just like last year, between one to three typhoons are expected to affect South Korea, but forecasters also warn there's a possibility of a super-typhoon due to the El Nino effect.
Lee Seung-jae, Arirang News.