Sweltering heat is forecast to continue to linger over the Korean Peninsula on Wednesday, with warnings remaining in place for most parts of the country.

The Korea Meteorological Administration said the scorching temperatures are projected to continue with the daytime heat index hitting 35 degrees Celsius.

Showers accompanied by wind, thunder and lightning are expected in the provinces of Gyeonggi, Gangwon, Chungcheong, Jeolla, Gyeongsang and the southernmost island of Jeju, with hourly precipitation of around 30 millimeters.

Following a tropical night, where temperatures stay above 25 degrees, morning lows on Thursday are expected to range between 23 and 28 degrees, while daytime highs are likely to peak at 33 to 37 degrees.

The stifling conditions earlier prompted the government to raise the heat crisis alert to the highest "serious" for the first time in four years.