Thirty Days Hath September

First recorded: 1562

Origin: England

Lyrics

Thirty days hath September,April, June, and November;All the rest have thirty-one,Excepting February alone,And that has twenty-eight days clear,And twenty-nine in each leap year.

Almost everyone still reaches for "Thirty days hath September" to settle how many days a month has, which makes it probably the most-used mnemonic in English. It is also very old: a version was written down around 1425, beside a list of saints' days, long before the calendar we use today was fixed.

Origins

The rhyme has a long history that predates its first printed publication. The earliest known English manuscript containing the verse dates to around 1425, where it was written alongside a list of saints' days. The mnemonic appeared in print for the first time in 1562 in Richard Grafton's book, Abridgment of the Chronicles of England, under the heading "A Rule to Know How Many Dayes Every Month in the Year Hath." Similar memory verses exist in other European languages, including French and Italian, indicating a broad pre-modern tradition of using verse to aid memory.

Meaning & Interpretation

The lyrics serve a purely practical purpose, assisting individuals in navigating the irregularities of the calendar systems. The month lengths were established in ancient Rome under Julius Caesar and Augustus, resulting in an irregular pattern of thirty and thirty-one-day months. The mnemonic acts as a simple checklist: September, April, June, and November have thirty days, February has twenty-eight days under normal circumstances, and all remaining months have thirty-one. The final lines explain the leap year cycle, where February gains a twenty-ninth day every four years. The use of the archaic verb "hath" instead of "has" highlights the Tudor-era origins of the printed text.

What is the origin of Thirty Days Hath September?

The rhyme originated as a medieval memory aid and was first recorded in writing in an English manuscript around 1425. It was first published in print in London in 1562 in Richard Grafton's Abridgment of the Chronicles of England.

Why do calendar months have different lengths?

The varying lengths of the months stem from the ancient Roman calendar reforms under Julius Caesar. The irregular lengths were designed to align the twelve-month year with the solar cycle of approximately 365.25 days, necessitating memory aids like this rhyme.