The highest-level heat wave warning was issued for Seoul for the first time Tuesday, as continued scorching heat is expected to push the capital's daytime temperature to 38 C. The serious heat wave warning had been issued for the southeastern and southwestern areas of Seoul as of 11 a.m., according to the Korea Meteorological Administration. Consequently, 11 wards in the capital, including Gangnam, Songpa, Gangseo and Gwanak, came under the influence of the warning, which was first introduced to the nation's heat wave advisory system on June 1. A serious heat wave warning is issued when the highest perceived temperature reaches 38 C or higher, or the maximum daily temperature reaches 39 C or higher, in an area where the highest perceived temperature is 35 C or higher for two or more consecutive days. As the heat wave has intensified, 18 additional heat-related illness cases were reported in Seoul on Monday, government data showed, bringing the city's cumulative total since May 15 to 185, including two deaths. The Seoul metropolitan government said it was closely monitoring the rise in hea