Since ancient times, in August of the old calendar (around September in the newer Gregorian calendar), the air is dry and the moon is clearly seen, and it is not too cold even at night with lower humidity; this has been regarded as the best time of year for moon viewing.
古来より8月(旧暦)（グレゴリオ暦（新暦）では9月ごろ）は、空気が乾燥して月が鮮やかに見え、かつ、湿度も低く夜でもそれほど寒くないため、観月に最も良い時節とされていた。