A man in his 20s died on Tuesday from what is thought to be an acute reaction from extreme heat exposure, raising the nationwide death toll due to heat-related illnesses to 22 as of Thursday.

Twenty-two people have died of the 2,570 who have been diagnosed with heat-related illnesses since May 20 until 4 p.m. Thursday, according to the Korea Disease Control and Prevention Agency's latest tally during what has been one of the most severe heat waves in recent years. The total number of people who have suffered from heat-related illnesses so far has already surpassed the 2,200 diagnosed in all of 2023.

The latest fatality due to the searing heat wave occurred after the 20-something man had installed an air conditioner at a middle school cafeteria in South Jeolla Province at 4:40 p.m. on Tuesday. He said he felt dizzy and was taken to a nearby hospital for emergency treatment but died, marking the second death in the province due to the heat.

Unrelenting heat has scorched the country day and night, as Seoul experienced its 25th tropical night in a row from Wednesday night to Thursday morning. It is the second-longest streak of tropical nights in recorded history for the city, with the current record of 26 days in 2018 being just one day longer. If tropical nights continue in Seoul as predicted, the city will break its record Friday night to Saturday morning.

Tropical night refers to when the temperature does not drop below 25 degrees Celsius from 6 p.m. at night to 9 a.m. the next morning.

The southern port city of Busan has already tied its record for the longest streak of tropical nights ever, with its 21st tropical night from Wednesday night to Thursday morning. The previous record was set in 1994 and reached again in 2018.

As the heat wave has persisted, 779,000 livestock have died from extreme heat and 1.03 million fish have died in aqua farms as of Wednesday.