Heat wave alerts have been issued for most parts of the country including Seoul.

Advisories have been upgraded to warnings in the eastern coast of Gangwon Province as well as Daegu, North Gyeongsang Province and Jeju Island. 

Afternoon highs on Wednesday will hover above 30 degrees Celsius in most regions, including 31 in Seoul, 33 in Gangneung and 35 in Daegu. 

The mercury level will remain above 25 degrees Celsius at night as well in many areas on Wednesday. Such muggy evenings are referred to as "tropical nights" in Korea. 

The monsoon rain will briefly let up Wednesday and Thursday, but showers are in store in most areas including Seoul. It's currently raining in Busan and Ulsan while sporadic showers are reported in South Chungcheong Province.

Strong showers of over 30 millimeters per hour accompanied by thunder and lightning are expected in some areas, calling for precaution.