SEOUL: South Korea registered its highest temperature since records began more than a century ago on Sunday (Aug 2), as authorities warned people to "immediately" stop all outdoor activities in affected areas. The southeastern city of Yangsan saw the temperature reach 42.5°C at 1.26pm local time (12.26pm, Singapore time), the Korea Meteorological Administration said on its website. An emergency alert is issued when areas experiencing a heatwave are forecast to hit perceived temperatures of 38°C or an actual temperature of 39°C for the day. Issuing a heat warning, the weather agency urged people to "immediately stop all outdoor activities", adding that "indoor spaces without air conditioning are dangerous". A heatwave day is defined as one with a maximum temperature of at least 33°C.