In August 2026 the son-eomneun days fall on 1, 2, 11, 12, 21, 22, 31. 7 in all. These are days whose lunar date ends in 9 or 0 — long the first thing people check before moving house or opening a shop.
August 15: 광복절; August 17: 대체공휴일(광복절). Taken from Korea Astronomy and Space Science Institute open data.
August 7: 입추; August 23: 처서. Computed from the sun's ecliptic longitude, not looked up in a table.
These dates hold for every visitor. A son-eomneun day is fixed by the lunar calendar alone and has nothing to do with your birth chart. What a given day means for you needs a birth date — there is no auspicious day that holds for everybody.