The nationwide heat wave has led to a surge in the number of patients with heat-related illnesses to 1,546, while causing the deaths of over 257,000 livestock, the interior ministry said Monday.

The previous day, temperatures in Yeoju, 64 kilometers southeast of Seoul, reached 40 C, marking the first time since 2018, which was recorded as the hottest year on record.

The interior ministry said that the total number of patients with heat-related illnesses from May 20 to last Saturday reached 1,546, 10 more than last year's figure.

During the period, 11 people died from illnesses caused by extreme heat.

The heat wave also killed 257,483 livestock from July 11 to last Saturday, including 235,880 poultry.

Additionally, 5,867 flatfish from six fish farms died due to the heat.

The weather agency has said that the current heat wave is expected to continue for at least another 10 days, with daytime temperatures remaining above average, ranging from 30 C to 36 C across the country.

Last week, the interior ministry issued its highest heat wave warning of "serious" and upgraded its response posture to Level 1, also the highest level.

The ministry advises people to avoid outdoor activities between 2 p.m. and 5 p.m. and seek cool places if they feel dizzy, nauseous or have a headache.