September starts two years at once. The school year opens on the first, and in most years Rosh Hashanah arrives within the same few weeks, so the Hebrew date takes a new number too. It is the month the word "beginning" gets attached to twice over.
It is also the month whose name does not add up: September means "the seventh", and it is the ninth. It shares that oddity with the three months after it, and, surprisingly, with the Hebrew calendar itself.
Where the name comes from: why "the seventh" is ninth
September comes from the Latin septem, seven. In the old Roman calendar the year opened in March, and on that count it really was the seventh month. Later two months were added at the front of the year, January and February, which Roman tradition credits to King Numa Pompilius, and every numbered month shifted two places. Nobody bothered to rename them, and so September through December are stuck two steps behind themselves forever.
There were attempts to change the names, though for other reasons. The Senate offered to name September after Tiberius; he refused, asking what they would do once there were thirteen Caesars. Domitian was less modest and renamed September Germanicus and October Domitianus, and the moment he died, the old names came back.
The Hebrew calendar lives with exactly the same anomaly: the Torah calls Nisan "the first month", yet the Hebrew year opens in Tishrei, which on that count is the seventh.
The season in Israel: a summer in no hurry to leave
September in Israel is not autumn. It is summer beginning to come apart, and for its first half it is indistinguishable from August: 30–31°C on the coast, high humidity, a sea still at 29°C.
What really marks September out is the sharav. These are hamsin events, a dry easterly wind that pushes the temperature up all at once and drops humidity into single figures, and they are especially common in this month. More often than people expect, the hottest day of the entire year is recorded in September rather than in July or August.
In the second half the month starts to open up: hill nights fall below 20°C, a cool damp appears before dawn, and the day shortens fast. The equinox lands on 22 or 23 September, and from then on the night is the longer half. Rain is still almost absent; a shower at the end of September is a trailer, not the first real rain.
September around the world
September is a month of going back and of gathering in. Half the northern hemisphere returns to school, and the fields are harvested.
In China and Vietnam it holds the Mid-Autumn Festival, the moon festival: lanterns are lit, mooncakes are handed round, and everyone goes out to look at the full moon. It too drifts between September and October, and for exactly the reason the Tishrei festivals drift: the Chinese calendar, like the Hebrew one, is lunisolar, and the festival is fixed to the fifteenth of the lunar month, which is to say to a full moon.
On 11 September Ethiopia celebrates Enkutatash, its new year, at the end of the rainy season with the fields full of yellow daisies. And in Munich, in comic contradiction of its name, Oktoberfest opens in the middle of September and only finishes in October.
The Jewish festivals that fall in September
September and October are the calendar's extreme case: the whole run of Tishrei festivals is packed into the two of them, and the split between them changes from year to year. The Hebrew year is about eleven days shorter than the civil one, so every Hebrew festival drifts across a window of roughly a month, and what fell in September this year can fall in October the next.
Rosh Hashanah: 1 and 2 Tishrei, landing anywhere from early September to early October. Two days kept as one long day, and the point from which the new Hebrew year is counted. Rosh Hashanah page.
Yom Kippur: nine days later, on 10 Tishrei; usually September, sometimes October. The longest fast of the year, and the day the whole country stops. Yom Kippur page.
Sukkot: begins on 15 Tishrei, five days after Yom Kippur, and in the earlier years it opens while September is still running. Sukkot page.
Before all of them sits Elul, the month of preparation, which covers the start of September in most years. The grid at the top of this page shows exactly how September splits between Elul and Tishrei in the year selected, and the button above it prints the month to a single page. For the full list there is the annual holiday calendar; for the current month, the home page.
Common questions about September
How many days are in September?
Thirty. September opens the alternating run that closes the year: 30, 31, 30, 31.
Which Hebrew months fall in September?
Elul and Tishrei, plus the end of Av in years when the Hebrew calendar runs late. The border between them is Rosh Hashanah.
Why does Rosh Hashanah move between September and October?
Because the Hebrew year is built on lunar months and runs about 354 days, eleven short of the civil year. The gap is corrected by adding a thirteenth month seven times in every nineteen years, which leaves 1 Tishrei drifting between 5 September and 5 October. This year Rosh Hashanah falls on 4-5/10/35.
Why is September called that if it is the ninth month?
The name comes from septem, seven, from the old Roman year that began in March. When January and February were added at the front, the numbered names were left as they were.
When does the Israeli school year start?
On 1 September, at every grade level.