The hot weather is expected to begin in earnest, with Korea's weather forecaster on Sunday issuing the first heat wave advisory of the year throughout Seoul and eastern Gyeonggi Province.

The Korea Meteorological Administration issued a heat wave advisory for all parts of Seoul and eastern Gyeonggi Province on 11 a.m. on Sunday. The warning is issued when the daily maximum sensory temperature is expected to be over 33 degrees Celsius for more than two consecutive days.

The Seoul Metropolitan Government said it will operate a comprehensive support situation committee as the first heat wave warning was issued this year. Emergency relief supplies will be prepared and monitoring will also be conducted to protect vulnerable communities, such as the elderly living alone or the homeless.

"As the number of days with heat waves is increasing due to global warming, we will immediately operate the heat wave comprehensive support situation committee to take care of citizens," said Choi Jin-seok, head of the Seoul Metropolitan Government's safety office.

The Korea Disease Control and Prevention Agency added that people should take precautions for heat-related diseases. A total of 86 people reported that they suffered from heat-related diseases from May 20 to Thursday, and one of them died, according to the KDCA. This was compared to 77 individuals during the same period last year, but the first death this year was recorded earlier on May 21. The first death from a heat-related disease last year occurred on July 1.

Those exposed to extreme heat for an extended period of time can experience symptoms such as headaches, dizziness, muscle cramps and fatigue.

In order to prevent heat-related diseases, it is helpful to reduce outdoor daytime activities as much as possible when a heat wave warning is issued and to wear hats and bright and loose clothes. People should drink water regularly, and those with symptoms like dizziness, headache and nausea, should be moved to a cool place immediately, the KDCA said.