People lay down on benches to cool off at an outdoor plaza in Busan, Tuesday. Yonhap

A heat wave warning was issued for most parts of Korea, Wednesday, as searing heat kicked off after the end of a period of heavy rainfall, according to the weather agency, Wednesday.

The nation will receive strong sunlight and high humidity, with the highest apparent temperature reaching 35 degrees Celsius at midday, due to the influence of the North Pacific anticyclone, the Korea Meteorological Administration (KMA) said.

A heat wave warning was issued for most parts of the country as of 10 a.m., with the southeastern city of Busan under a heat wave warning for the first time this year.

Currently, 173 out of 183 land special warning areas nationwide have been issued heat warnings.

The Ministry of the Interior and Safety issues the alert when the daily temperature covers more than 40 percent of the country and reaches 33 degrees or higher for more than two days.

As Typhoon Gaemi pushed the North Pacific High northward, and the stagnant front followed suit, Korea was then placed on the edge of the North Pacific High away from the stagnant front.

As a result, it is expected that the heat wave will continue in most regions for the time being.

During the day, as the ground temperature rises, the atmosphere will become unstable, triggering occasional showers.

Tropical nights will continue. A night is considered tropical when temperatures do not fall below 25 degrees from 6 p.m. to 9 a.m. the next day.

It is recommended for people to refrain from outdoor activities and take special care against food poisoning in such hot weather.

Also, it is recommended to drink water frequently and take regular breaks when working outdoors.

According to the KMA, there has been only one day this month, as of Monday, with scorching heat defined by a daily maximum temperature of 33 degrees or higher. It is not the strong sunlight but the high temperature with humid southwesterly winds that has caused the humid heat wave.

According to the KMA's calculations, the ambient temperature matches body temperature when humidity is at 55 percent. Additionally, the ambient temperature increases by approximately 1 degree for every 10 percent increase in humidity.