South Korea’s summer has felt less oppressive than usual so far, thanks to a delayed monsoon and lower humidity. But that brief relief may not last. Weather experts say the country could face stronger heat after the rainy season ends, as two high-pressure systems may expand over the Korean Peninsula and trap hot air near the ground. According to the Korea Meteorological Administration, Seoul’s average humidity in June was 61 percent, lower than last year’s 70 percent and the long-term average of