( Yonhap ) The summer weather has officially arrived , and on Tuesday Seoul got its first heat wave advisory of the year . The Korea Meteorological Administration issued the alert effective 11 a . m . Tuesday for eastern Seoul , three regions in Gyeonggi Province and Cheongju , North Chungcheong Province . “ A lot of regions will see their maximum sensory temperature for the day exceed 33 degrees Celsius through Wednesday while a number of regions , including Seoul , are issued heat wave alerts , ” the KMA said . A heat wave advisory is issued when the daytime high is expected to reach 33 degrees Celsius for two consecutive days . A warning , stronger than an advisory , is issued when the forecast temperature is 35 degrees Celsius or higher . The KMA ’ s alert system was revised recently to take humidity into account and reflect how hot the weather feels . Previously , alerts were based solely on actual air temperatures .   The season ’ s first hot weather alert was issued Sunday for Daegu and a number of other regions in the central part of the country . The first warning was issued Monday for Gyeongsan , North Gyeongsang Province , where the temperature hit 37 . 5 degrees Celsius .   While the monsoon season is expected to start later this month , the KMA said rainclouds were approaching Jeju Island , which might experience its rainy season before the rest of the country . The authorities are heightening precautions against COVID - 19 for the summer , warning that the pandemic is not over . Earlier this month the Ministry of Food and Drug Safety fast - tracked approval for a new type of face mask designed for summertime use for healthy people in low - risk settings . The manufacturer , Wellkeeps , said earlier that the new summer masks would hit the shelves nationwide later this month . By Ko Jun - tae ( ko . juntae @ heraldcorp . com ) [ 네이버 에서 코리아 헤럴드 구독 ] ▶ KH Podcast    ▶ KH Video <ⓒ KoreaHerald ( www . koreaherald . com ) 무단 전재 및 재 배포 금지 >