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The Months That Count Wrong

September means seven, yet it sits ninth, and that small lie has outlasted Rome, Charlemagne, and a revolution. How did a goat-god, a two-faced doorway, and two dead politicians end up ruling your calendar?

10 chapters · 6 sourcesBy GinaPublished November 3, 2026

Questions about this story

Why do the Roman calendar month names September through December mean seven through ten?

In the earliest Roman calendar, the year began in March, making September through December the seventh through tenth months. Their names derived from the Latin numbers septem, octo, novem, and decem. When the Roman Senate shifted New Year's Day to January in 153 BCE, the original numerical names were permanently kept despite being two places off.

Why did the Roman Senate move New Year's Day from March to January in 153 BCE?

The Roman Senate moved the start of the civil year to January 1 to dispatch military commanders sooner for the Second Celtiberian War in Hispania. Consuls previously took office in mid-March, leaving too little time to raise armies and reach Spain before the campaigning season ended.

How did July and August get their modern names on the Roman calendar?

July was originally Quintilis, the fifth month, and was renamed Iulius in 44 BCE after Julius Caesar was assassinated. August was originally Sextilis, the sixth month, and was renamed Augustus in 8 BCE to honor Emperor Augustus's military and political victories, including his first consulship and conquest of Egypt.

Did Augustus steal a day from February to make August 31 days long?

No, Augustus did not steal a day from February. A painted Roman calendar from around 84 BCE, the Fasti Antiates Maiores, proves that Sextilis already had 31 days long before Augustus received the honor. The story of Augustus stealing a day was invented in the thirteenth century by Parisian scholar Johannes de Sacrobosco.

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Period: 753 BC - 1793 · 15 minutes · English · two hosts

c. 753 BCE

New Year in March

Vestal Virgins relit the sacred fire on March 1
March once opened the Roman year
Month names still carry the old order

Ada: It's the first of the month in early Rome, and the air still has winter in it. Inside a small round temple, the Vestal Virgins are putting out a fire that has burned all year, and kindling a new one in its place.²⁴

Theo: They're deliberately extinguishing the sacred flame? That feels like the opposite of what you'd want a sacred flame to do.

Ada: That's the point. The old year is over, the state is reborn, and the fighting season can begin again. This is the Kalends of March, and in the oldest Roman reckoning, this is New Year's Day.²⁴

Theo: March as the start of the year. So the whole thing was shifted.

Ada: It was, and the fingerprints are still on your wall calendar. September means seventh. December means tenth. They're just sitting in the wrong seats.³⁵

Theo: I'm Theo.

Ada: And I'm Ada, and this is Historai. Gina, every month you name is a little fossil, and today we dig all twelve of them up.

c. 753 BCE

The Romulan Calendar

Ten months, 304 days
Winter left uncounted, about 61 days
Some historians call the scheme a later myth

Ada: Tradition credits the first calendar to Romulus, around seven fifty-three BC. Ten months, three hundred and four days: March, April, May, June, then Quintilis, Sextilis, and September through December.²³

Theo: Hang on, that doesn't add up to a year. Where did the rest of the days go?

Ada: Into a hole. After December there was just a roughly sixty-one day gap of winter that nobody bothered to count. No farming, no campaigns, so no months.³⁴

Theo: They literally left winter off the calendar. That's the most relatable thing Rome ever did.

Ada: Now, I should flag: some modern historians, Jörg Rüpke among them, argue that this neat ten-month scheme was invented later by Roman antiquarians looking backward, not a calendar anyone actually lived by.

Theo: So the origin story of the calendar might itself be a story.

Ada: It might. But the numbers in the names are real, and they only make sense if you start counting from March.

c. 700 BCE

Numa Adds Two Months

January and February fill the winter gap
Odd lengths chosen for luck, February the exception
Intercalary Mercedonius kept it aligned

Ada: Enter Rome's second king, Numa Pompilius, reigning by tradition from seven fifteen to six seventy-three BC. He takes that dead winter and gives it two months: January and February.²³

Theo: So now we're at twelve. Why do the months have such odd lengths, though, twenty-nine, thirty-one, twenty-eight?

Ada: Because early Romans thought even numbers were unlucky. Numa made the months odd on purpose. March, May, Quintilis, and October got thirty-one days, most of the rest twenty-nine.²³

Theo: And February drew the short straw at twenty-eight.²³

Ada: It did, which breaks the lucky-odd rule, but somebody had to. That gave a lunar year of three hundred and fifty-five days.²³

Theo: Still ten days short of the sun. How did they patch that?

Ada: With a whole extra month, Mercedonius, shoved into February every so often by the priests. Twenty-two or twenty-three days, inserted whenever they felt the seasons drifting.²³

153 BCE

153 BC: January 1

Civil new year moved from March to January 1
Driven by the Celtiberian War in Hispania
The numbered months slipped out of place for good

Ada: For centuries the civil year still opened in March. Then, in one fifty-three BC, the Senate moved the start to the first of January.³⁴

Theo: Just like that? What was wrong with March?

Ada: Spain. The Second Celtiberian War broke out in Hispania, and consuls took office on the Ides of March, then had to raise armies and march west. By the time they arrived, the campaigning season was half gone.³⁴

Theo: So they moved New Year's up to get the generals out the door sooner. A scheduling fix.

Ada: Purely administrative. But that is the moment the mismatch gets locked in forever. September, the seventh month, now permanently sits ninth.³⁴

Theo: And nobody ever renumbered them to match.

Ada: Nobody. The names were older than the reason they'd stopped being true.

c. 700 BCE

January and February

January from Janus, two-faced god of doorways
February from februa, tools of purification
Lupercalia and Parentalia: cleansing and the dead

Ada: So now let's name them. January is Ianuarius, for Janus, god of beginnings and doorways. He's shown with two bearded faces, one looking back at the old year, one forward into the new.³⁵

Theo: The two-faced god of the threshold. That's a near-perfect name for the first of January.

Ada: The root is ianua, a door. January is literally the hinge of the year. February is darker. It comes from februa, the instruments of ritual purification.⁵⁶

Theo: Purification how, exactly?

Ada: The Lupercalia, February fifteenth. Priests sacrificed goats, cut the hides into strips, also called februa, and ran through Rome striking people to bring fertility and cleansing.²⁵

Theo: Being whacked with a goatskin as a blessing. I'll take a card instead.

Ada: February was the old year's final month, so it was for cleansing and for the dead, the Parentalia, when Romans made offerings to their ancestors.²⁴

c. 700 BCE

March to June

March from Mars, god of war and fields
April: aperire 'to open' or Etruscan Apru/Aphrodite
May and June: gods Maia and Juno, or elders and youth

Ada: March is Martius, for Mars, god of war and farming both, and the father of Romulus and Remus. The campaigning month, the city reborn.²³

Theo: And April? That one I've heard argued about.

Ada: You've heard right. Classical Romans linked Aprilis to aperire, to open, like buds opening in spring. Modern linguists think it more likely came through Etruscan Apru, from the Greek Aphrodite, their Venus.²⁵

Theo: So accounts differ, flowers versus the love goddess.

Ada: They do. May is Maius, maybe for Maia, an old growth goddess, maybe, said Ovid, from maiores, the elders. June is Iunius, probably Juno, goddess of marriage, which is why June weddings caught on.²⁵

Theo: Let me guess, Ovid had a rival theory for June too.

Ada: Of course. If May honored the maiores, the elders, then June honored the iuniores, the young men. He liked his symmetry.²⁵

44–8 BCE

July and August

Quintilis became July for Julius Caesar, 44 BC
Sextilis became August for Augustus, 8 BC
Caesar's reform gave 46 BC 445 days: the Year of Confusion

Ada: Now the old numbers start getting overwritten. The fifth month was Quintilis, from quintus, five. In forty-four BC, just after Julius Caesar was assassinated, Mark Antony proposed renaming it Iulius, for Caesar, whose birthday fell that month.³⁴

Theo: July. And Caesar's the one who'd just fixed the whole calendar, right?

Ada: Right. In forty-six BC, advised by the Alexandrian astronomer Sosigenes, he scrapped the clumsy intercalary months and set the year at three hundred and sixty-five days, with a leap day every four years.³⁴

Theo: Sosigenes of Alexandria. Our Alexander episode keeps paying dividends.

Ada: It does. But to reset the seasons first, Caesar stretched forty-six BC to four hundred and forty-five days. They called it the Year of Confusion.³⁴

Theo: And August? Let me guess, Augustus wanted one too.

Ada: In eight BC the Senate renamed Sextilis, the sixth month, Augustus. Not his birth month, that was September, but the month he'd won his first consulship, conquered Egypt, and ended the civil wars.²³

13th century CE

The February Myth

Sacrobosco invented the stolen-day tale in the 1200s
The Fasti Antiates Maiores already gives Sextilis 31 days
August's length predates Augustus's name

Theo: Okay, but I have to ask about the famous story. Augustus was jealous that July had thirty-one days, so he stole a day from February to make August thirty-one too. True?

Ada: Completely false, and we can prove it. That tale was invented in the thirteenth century by a Paris scholar, Johannes de Sacrobosco, in a treatise on reckoning the year.²³

Theo: So a medieval academic just made it up, and it stuck for seven hundred years.

Ada: It's a great story, which is exactly the problem. We have a painted Roman calendar, the Fasti Antiates Maiores, from around eighty-four BC.²³

Theo: And it already shows Sextilis with thirty-one days.

Ada: Already thirty-one, long before Augustus got his name on it. The lengths were set by Caesar's reform. Augustus stole nothing from February.²³

Theo: Poor February. Robbed by legend as well as by Numa.

37–192 CE

Renaming the Months

September–December simply mean seven to ten
Caligula, Nero, Domitian all tried to rename months
Commodus renamed all twelve; erased after his murder

Ada: Here's what I love. The numbered months, September through December, just mean seven, eight, nine, ten, with that -ber ending meaning pertaining to. And emperor after emperor tried to replace them.⁵⁶

Theo: Tried and failed, I'm sensing.

Ada: Spectacularly. Caligula renamed September Germanicus; gone when he died. Nero turned April, May, and June into Neroneus, Claudius, and Germanicus; erased the day he killed himself.³⁴

Theo: So the names only lasted as long as the emperor did.

Ada: Domitian renamed September and October after himself; the Senate restored them after his assassination. And then there's Commodus, who went all in.³⁴

Theo: How all in?

Ada: He renamed all twelve months after his own twelve titles: Amazonius, Invictus, Felix, and so on. On New Year's Eve of one ninety-two, he was murdered, and the Senate wiped every one of them out overnight.²⁴

Theo: Twelve months of ego, deleted in a single night.

8th–19th century CE

Why the Names Survived

Bede's Anglo-Saxon and Charlemagne's Frankish names faded
French Republican calendar lasted just 12 years
Latin month names remain the global standard

Ada: And then Rome itself falls, and the names don't. The Venerable Bede, an eighth-century monk, records Anglo-Saxon alternatives: Eosturmonath, which gives us Easter, and Blotmonath, blood month, when they slaughtered the herds.¹

Theo: Vivid. But those didn't win either.

Ada: They didn't. Around eight hundred, Charlemagne tried his own Frankish names, Wintarmanoth for January, Heuvimanoth, hay month, for July. Abandoned soon after he died.⁵

Theo: And the French Revolution took a swing too, didn't it? I remember Thermidor.

Ada: They did, in seventeen ninety-three. A whole poetic calendar, Brumaire, Floréal, Thermidor. Napoleon scrapped it on the first of January, eighteen oh-six. Twelve years, done.³⁵

Theo: So a goat-god, a two-faced doorway, and two dead Roman politicians outlasted Charlemagne and a revolution.

Ada: Every time you say September, you're counting from a March that stopped being first over two thousand years ago. The names kept the memory even after everyone forgot the reason.

Theo: That's the thing about habit. It's more durable than empire.

Ada: Gina, whenever a name on your calendar makes you curious, you can pause any episode and just ask us. This was Historai, where history answers back.

Research record

Sources

sourcebooks.fordham.eduPrimary document
LacusCurtius • The Roman Calendar (Smith's Dictionary, 1875)Academic
The early Roman calendar | BritannicaEncyclopedia
The Athenian Calendar - World History EncyclopediaEncyclopedia
month | BritannicaEncyclopedia
oxfordreference.comEncyclopedia