By Kyu-seok Shim, Daewoung Kim and Dahyun LeeSEOUL, Aug 3 (Reuters) - A record heatwave is gripping the Korean Peninsula, sending temperatures soaring across South Korea and North Korea as authorities expand emergency measures and residents seek relief ‌in cooling shelters, beaches and water parks. Forecasters said on Monday that extreme heat, previously concentrated in South Korea's southeast, ‌was spreading to the Seoul metropolitan area and other western regions. North Korean state media also reported temperatures approaching 40 degrees Celsius (104 degrees Fahrenheit) in parts of ​the country and a fifth straight tropical night in Pyongyang. Advertisement AdvertisementSouth Korea's weather agency warned temperatures could rise further in western regions this week and said the heatwave and tropical nights were likely to persist. Seoul districts have expanded cooling shelters and distributed free water and sun umbrellas, while Yangsan has expanded water-spraying operations and water distribution.