Sextilis

Sextilis (lit. 'sixth') or mensis Sextilis was the Latin name for what was originally the sixth month in the Roman calendar, when March (Martius, "Mars' month") was the first of ten months in the year. After the calendar reform that produced a twelve-month year, Sextilis became the eighth month, but retained its name. It was renamed Augustus (August) in 8 BC in honor of the first Roman emperor, Augustus. Sextilis followed Quinctilis, which was renamed Julius (July) after Julius Caesar, and preceded September (from septem, "seven"), which was originally the seventh month.

Julius (July) was renamed from Quintilis ("fifth" month) in honor of Julius Caesar, who had adopted his grand-nephew Octavian, the future Augustus, and made him his heir. It has sometimes been thought that the month has 31 days because Augustus wanted as many days in his month as in his predecessor's, but Sextilis in fact had 31 days since the reform during Caesar's dictatorship that created the Julian calendar.

The decree of the Senate (senatus consultum) renaming Sextilis reads in part:

Whereas the emperor Augustus Caesar, in the month of Sextilis, was first admitted to the consulate, and thrice entered the city in triumph, and in the same month the legions, from the Janiculum, placed themselves under his auspices, and in the same month Egypt was brought under the authority of the Roman people, and in the same month an end was put to the civil wars; and whereas for these reasons the said month is, and has been, most fortunate to this empire, it is hereby decreed by the senate that the said month shall be called Augustus.

The Calendar of Filocalus illustrated the month of August with a seasonal representation of summer's heat. A peacock fan overhangs a nude male who drinks from a large bowl, with his cast-off garment in the top right corner. The amphora beside him is sealed with a flower and in one extant copy is inscribed ZLS, probably a mistaken transcription for the Greek exhortation zeses, "to your health". Three mature gourds or melons are another seasonal motif.

The Romans did not number days of a month sequentially from the 1st through the last day. Instead, they counted back from the three fixed points of the month: the Nones (5th or 7th, depending on the length of the month), the Ides (13th or 15th), and the Kalends (1st) of the following month. The Nones of August was the 5th, and the Ides the 13th. The last day of August was the pridie Kalendas Septembris, "day before the Kalends of September". Roman counting was inclusive; 9 August was ante diem V Idūs Sextīlis (ante diem V Idūs Augustas), "the 5th day before the Ides of August," usually abbreviated a.d. V Id. Sext. (a.d. V Id. Aug.), or with the a.d. omitted altogether. The Julian calendar reform added two days to Sextilis; thus on the pre-reform calendar, 23 August was VIII Kal. Sept., "the 8th day before the Kalends of September," but on the Julian calendar X Kal. Sept., "the 10th day before the Kalends of September".

On the calendar of the Roman Republic and early Principate, each day was marked with a letter to denote its religiously lawful status. In August, these were:

Days were also marked with nundinal letters in cycles of A B C D E F G H, to mark the "market week" (these are omitted in the table below).