The Roman calendar, was a lunar based calendar with 12 months like our current Gregorian Calendar. The Julian Calendar replaced the Lunar Based Roman Calendar as a way to keep the seasons aligned with the months.

Caesar commissioned help in developing the Julian calendar. The reason for creating a new calendar was because the days of the month were no longer aligning with the seasons as the previous Roman calendar had drifted. 

In 44 BCE the Roman Senate renamed the month of Quintilis (Latin for 5th month since the Roman Calendar began in March) to Julius in honor of Julius Caesar, as it was the month of his birth. This was after Julius Caesar was asassinated on the Ides of March 44 BC. The calendar was officially activated on the First of January 45 BCE. 

The presently used Gregorian Calendar implemented in 1582 by Pope Gregory replaced the Julian calendar because the Julian Calendar was drifting one day every 128 years with the total drift being 10 days in 1582. The reason for this was due to the actual number of days in a solar year being 365.2425. This refinement in the days of the year was calculated by the Gregorian Calendar so that Leap years are not counted in years that end in 00. This Calendar is so accurate it only drifts one day in about 3300 years.

The new Gregorian Calendar kept the names of the months from the Julian Calendar including July as the seventh month and August for Augusta Caesar as the 8th month.

Originally, the Roman Calendar had only 10 months with names. They considered winter as an inactive time so they only had names for March through December. March, April, May and June are connected to Roman dieties.

The rest of the Roman Calendar months were numbered in Latin. Our current July was the fifth month (Quintilis). Our current August was the sixth month (Sextilis). September was the seventh month, October was the eighth month, November was the ninth month, and December was the tenth month.

As time progressed January (Januarius) and February (Februarius) were added to the end of the year, giving all 12 months an identifying name.

The Creation of the Julian Calendar or Solar Calendar
When Julius Caesar became Pontifex Maximus, he got help reforming the Roman calendar so that the 12 months were based on Earth’s revolutions around the Sun creating a Solar Calendar – replacing the Lunar Calendar that was no longer aligned with the seasons. That is when January and February were moved to the front of the year, and this Julian Calendar included leap years to keep a better alignment with the Solar year.

The winter months (January and February) remained a time of reflection, peace, new beginnings, and purification. After Caesar’s death, the month Quintilis was renamed July in honor of Julius Caesar in 44 BC, and later, Sextilis was renamed August in honor of Roman Emperor Augustus in 8 BC.

Of course, all the renaming and reorganizing meant that some of the months’ names no longer agreed with their position in the calendar (September to December, for example). Later, emperors tried to name various months after themselves, but those changes did not outlive them!

The Gregorian Calendar
In 1582, Pope Gregory XIII introduced many reforms to the Julian calendar, as there were still some inaccuracies and adjustments to be made. Mainly, the Julian calendar had overestimated the time it took the Earth to orbit the Sun, so the Gregorian calendar shortened the calendar year from 365.25 days to 365.2425 days. This meant that the calendar could be more easily corrected by leap years.

Origins of the Months’ Names

JANUARY
Named for the Roman god Janus, protector of gates and doorways. Janus is depicted with two faces, one looking into the past, the other into the future. In ancient Roman times, the gates of the temple of Janus were open in times of war and closed in times of peace.

FEBRUARY
From the Latin word februa, “to cleanse.” The Roman calendar month of Februarius was named Februalia, a festival of purification and atonement during this period.

MARCH
Named for the Roman god of war, Mars. This was the time of year to resume military campaigns interrupted by winter. March was also a time of many festivals, presumably in preparation for the campaigning season.

APRIL
From the Latin word aperio, “to open (bud),” plants begin to grow in this month. In essence, this month was viewed as spring’s renewal.

MAY
Named for the Roman goddess Maia, who oversaw the growth of plants. Also, from the Latin word maiores, “elders,” who were celebrated during this month. Maia was considered a nurturer and an earth goddess, explaining the connection with this springtime month.

JUNE
Named for the Roman goddess Juno, patroness of marriage and the well-being of women. Also, it comes from the Latin word juvenis, meaning “young people.”

JULY
Named to honor Roman dictator Julius Caesar (100 B.C.– 44 B.C.) after his death. Two years prior to his death in 46 BCE Julius Caesar made a significant contribution to how we track the solar year: With the help of Sosigenes, the Julian Calendar was developed. It was the precursor to the Gregorian calendar we use today.

AUGUST
Named to honor the first Roman emperor (and grandnephew of Julius Caesar), Augustus Caesar (63 BCE– CE 14). Augustus (the first Roman emperor) comes from the Latin word augustus, meaning “venerable, noble, and majestic.”

SEPTEMBER
September comes from the Latin word septem, meaning “seven,” because it was the seventh month of the early Roman calendar. It is now the 9th month of the Solar Year.

OCTOBER
In the ancient Roman calendar, October was the name of the eighth month of the year. Its name comes from octo, the Latin word for “eight.” When the Romans converted to a 12-month calendar, they tried to rename this month after various Roman emperors, but to this day this month is known as October.

In Old England, the month was called Winmonath, meaning “wine month,” for this was the time of year when wine was made. The English also called it Winterfylleth, or “Winter Full Moon.” They considered this full Moon to be the start of winter. In weather lore, we note, “If October brings heavy frosts and winds, then will January and February be mild.”

NOVEMBER
From the Latin word novem, “nine,” this had been the ninth month of the early Roman calendar.

DECEMBER
From the Latin word decem, “ten,” this had been the tenth month of the early Roman calendar.

The last 4 months of our Calendar year are no longer connected to the number their latin names suggest. In 2026 we have had the Gregorian Calendar for 444 years so it is unlikely the names of these months will be adjusted to fit their actual placement in the Solar Calendar that has been used for so long.