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Rome’s first calendar -

The Gregorian calendar that we know and use today is built on the foundations of the Roman calendar. The earliest Roman calendar only had 10 official months, beginning with March and ending in December. The winter months were uncounted, since people could not plant or harvest crops during that time.

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A year -

This primitive calendar totaled only 304 days, which left over 60 days unaccounted for during winter. Rome’s second king, Numa Pompilius, is credited with adding January and February, thus expanding the calendar to 12 months. His reforms were both religious and practical, aligning timekeeping more closely with lunar cycles and political needs.

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A lunar system -

Despite the updates, the Roman calendar remained lunar-based, which caused it to drift out of alignment with the seasons. Rome used an awkward system of intercalary months, added irregularly by priests to reset the year’s balance.

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Calendrical intervention -

By 46 BCE, the Roman calendar had drifted so badly that general Julius Caesar, advised by Alexandrian astronomers, overhauled the entire system. His Julian calendar replaced lunar calculations with a stable, sun-based 365-day year.

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Correcting the math -

But the issue wasn’t entirely solved. The Julian calendar assumed the year was 365.25 days long, which is why another day was added every four years. But it was actually slightly shorter, which led to an 11-minute annual discrepancy that added up over time.

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A bold reset -

In 1582, Pope Gregory XIII introduced the Gregorian calendar, dropping 10 days from October to realign the calendar with the equinox. This was a radical shift, met with admiration, confusion, and, in some places, resistance.

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A smarter leap year system -

To keep better solar accuracy, the Gregorian calendar refined leap years. Unlike the Julian system, it excluded leap years in century years that are not divisible by 400. This cut down the error to just 26 seconds per year.

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A global adoption -

As time passed, the Gregorian calendar slowly became the international civil standard for many parts of the world. Today, only four countries have not adopted the calendar: Afghanistan, Iran, Ethiopia, and Nepal.

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Roman roots -

The actual months of the year obtained their names from various sources. Essentially, the impact of Roman culture on the calendar can be felt in every month, but each one has a different reason for existing based on where they are positioned in the year. Let’s see what they are.

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January -

January is named after Janus, the Roman god of doors and transitions, whose two faces symbolize looking to the past and future. This is perfect for the first month of the calendar, as one of Janus’ faces looks to the previous year and the other looks to the new.

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January -

The god Janus was believed to represent choices and change, with his faces often placed on gateways. As the first month, January sets a tone of reflection and ambition, which mirrors Janus’ dual gaze toward what was and what will be.

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February -

The month of February comes from Februa, a Roman purification festival that was held mid-month. It was a time to cleanse the spirit and home in preparation for the approaching spring, and was meant to act as the catalyst to a fresh, renewed time.

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February -

February’s name reflected deeper themes of healing and moral reset. Romans believed Februa ceremonies could purify a person or city, which made February a sacred interval for spiritual and societal cleanliness.

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March -

March is named after the Roman god of war, Mars. As spring returned to the Northern Hemisphere, this was the time when military campaigns resumed, linking the month with vigor, movement, and the spirited advance of armies.

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March -

March represented rebirth not just agriculturally, but in power. The god Mars was more than a warrior: he symbolized the force of action, which makes this month one of fresh starts and assertive physical energy.

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April -

April’s name likely stems from the Latin word aperire, which means “to open.” Historians believe that this refers to the flowers and buds blooming. The month signified nature’s awakening, with fields and trees emerging from winter’s long slumber.

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April -

Some Romans associated April with Aphrodite (Venus), the goddess of love. This tie reinforced the month’s ongoing themes of fertility and beauty, as April's soft warmth encouraged romance, growth, and the lush rebirth of landscapes.

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May -

The fifth month of the year is named after Maia, a Roman earth goddess linked to fertility and growth (pictured with her son, Hermes). Her nurturing spirit fit the season’s natural expansion, as crops rose and greenery flourished under warmer, lengthening days.

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May -

Maia’s presence made the month of May symbolic of gentle strength. Romans honored the goddess during this month to bless agricultural bounty and maternal care, aligning perfectly with spring’s sense of blooming life and tender vitality.

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June -

June gets its name from Juno, queen of the gods and the goddess of marriage and childbirth. Her association made the month of June a favored time for weddings and new beginnings, especially among Roman nobility.

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June -

Juno's oversight was believed to bring order and blessings to families. June’s placement in the heart of the year made it ideal for unions, as the goddess ensured protection and harmony for couples starting their journeys together.

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July -

Originally called Quintilis, the seventh month of the year was renamed July in honor of Julius Caesar after his assassination in 44 BCE. He was the one to originally reform the calendar, and this renaming immortalized his legacy in the structure of time itself.

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July -

Julius Caesar’s contributions to the Julian calendar were pivotal. Naming July after him signified not just personal tribute, but marked his influence in creating a more accurate, sun-based calendar for the empire.

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August -

The month of August was once called Sextilis, but was renamed to honor Augustus Caesar, the first Roman emperor, in 8 BCE. The change aligned the month with imperial dignity, ensuring Augustus’ glory was commemorated with warmth and sunlight.

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August -

This renaming continued the trend of embedding rulers into time itself. Augustus’ successful campaigns and golden rule made this month a symbol of prosperity, balance, and peak summer vitality in Roman tradition.

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September -

September’s name comes from septem, the Latin word for “seven.” Despite September being the ninth month in the year, it was originally the seventh in the Roman calendar. The name was never updated after calendar reforms.

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September -

The name for September stuck even after January and February were added. September’s numeric label is a remnant of an older world, preserving the linguistic echo of Rome’s early timekeeping traditions and original calendar structure.

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October -

Like its predecessor, October stems from octo, Latin for “eight.” It was once the eighth month, and, even though its position shifted, the name continued as a nod to Rome’s early system.

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October -

In Old England, October was known as Winmonath, meaning “wine month,” since it marked the season of winemaking. It was also called Winterfylleth by the English, or “Winter Full Moon,” believed to signal the true beginning of winter’s arrival.

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November -

November is named from the Latin word novem, meaning “nine.” Since the calendar once began in March, this was originally the ninth month, and it has since been shifted to its current 11th placement.

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November -

Though not tied to gods or emperors, November’s identity reflects Rome’s functional beginnings. As the year waned, this month symbolized endurance, a quiet progression towards winter’s arrival and the year's final chapter.

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December -

December comes from decem, Latin for “ten,” marking its original spot as the last month of the Roman year. It concluded the annual cycle before January and February were added much later on.

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December -

December retained its numerical name even as it became the 12th month. Its title marks the calendar’s ancient finale, a historical holdover that is wrapped in festivities, closure, and the winter solstice’s turning point.

Sources: (British Museum) (The Old Farmer’s Almanac) (Britannica)

See also: How the days of the week got their names

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