Season of the Harvest

The Season of the Harvest or Low Water was the third and final season of the lunar and civil Egyptian calendars. It fell after the Season of the Emergence (Prt) and before the spiritually dangerous intercalary month (Ḥryw Rnpt), after which the New Year's festivities began the Season of the Inundation (Ꜣḫt).

The Season of the Harvest was known to the Egyptians themselves as "Low Water" (Egyptian: ), variously transliterated as Shemu or Shomu, in reference to the state of the Nile before the beginning of its annual flood.

It is also referred to as Summer or the Dry Season.

In the lunar calendar, the intercalary month was added as needed to maintain the heliacal rising of Sirius in the fourth month of this season. This meant that the Season of the Harvest usually lasted from May to September. Because the precise timing of the flood varied, the months of "Low Water" no longer precisely reflected the state of the river but the season was usually the time for the collection of Egypt's grain harvest.

In the civil calendar, the lack of leap years into the Ptolemaic and Roman periods meant the season lost about one day every four years and was not stable relative to the solar year or Gregorian calendar.

The Season of the Harvest was divided into four months. In the lunar calendar, each began on a dawn when the waning crescent moon was no longer visible. In the civil calendar, each consisted of exactly 30 days divided into three 10-day weeks known as decans.

...
Wikipedia