How many month are in a year

Mariana Holostenco  January 21, 2022

how many month in a year

Each year has 12 months; these are January, February, March, April, May, June, July, August, September, October, November, and December.

How many months in a Leap year? Have you ever wondered that? The answer is the same: 12 months. The difference between the Common year and the Leap year is given by a single day, namely, February 29.
  • Common years have 365 days and the month of February has 28 days.
  • Leap years have 366 days and the month of February has 29 days.

The names of the months

The names of the months were given according to different factors over time. For example, the names of some months simply refer to the serialized number that they had in the calendar at that time. In this situation is, for example, the month of September, whose name comes from the fact that it was the seventh month of the calendar of Romulus 750 BC (the oldest known Roman calendar).

August, however, received its name from the glory of Rome's ruler Caesar Augustus, in 8 BC. It should be noted that, previously, in the 10-month calendar of the Romans, it was the sixth month and was called Sextilis. Other months, such as March and May, were named after various deities.


The name of this month comes from Roman mythology. John was the god of beginnings and transitions. His name was given to this month precisely because January was introduced at the beginning of the year.,/


The name of this month means "purification" and comes from ancient Rome. It has to do with “februum,” which were purification instruments used to purify cities during a pastoral festival named Lupercalia or “dies Februatus.”,/


Taken from ancient Roman mythology, the name belongs to the deity Mars. He was both the god of war and the protector of agriculture.


The name is supposed to derive from the verb "aperire" (to open), or from the Greek goddess Aphrodite, the equivalent deity of the Roman goddess Venus


There are two assumptions related to its origin. On the one hand, it is supposed to come from the name of the Greek goddess of fertility, Maia. On the other hand, it is supposed to come from the Latin word "maior," which means "elders."


Consistent with the assumption related to the name of May, it is assumed that the name of June comes from the Latin "iuniores," which means "young ones." However, there is also the assumption that June was named after the Roman goddess of marriage, Juno (the wife of Jupiter).


Originally called Quintilis, this month was renamed Augustus to honor the first Roman emperor, Caesar Augustus.


In 8 BC, the month originally called Sextilis was renamed Augustus to honor the first Roman emperor, Caesar Augustus.


Its name is a remnant from the time when it was the seventh month of the year in the calendar of Roman antiquity. Although later its place in the calendar changed, the name of the month remained the same.


As in the case of the previous month, it was named after its order in the ancient Roman calendar.


The name comes from the Latin “novem,” meaning "nine." This represents how many months it was in the calendar until the Julian Reformation


It means “ten” and comes from the Latin "decem." Although it later became the twelfth month of the year, the name has been retained.

Numbering the months of the year

1. January, the first month

This month did not exist in the ancient Roman calendar until around 713 BC. At that time, the first month of the year was considered March, because winter was considered as such, without months.

2. February, the second month

It was introduced to the calendar along with January, by Numa Pompilius around 713 BC.

3. March, the third month

March was the first month of the year in the calendar of Roman antiquity. With the introduction of the months of January and February into the calendar, March became the third month.

4. April, the fourth month

Although it was the second month of the year in the initial calendar (the 10-month calendar), with the introduction of January and February, it became the fourth.

5. May, the fifth month

It is the fifth month in the Gregorian calendar, the one we use today, but in the calendar of Roman antiquity, it was the third month of the year of 10 months.

6. June, the sixth month

By the mid-40s, this month was the fourth month in the calendar and had 29 days. Following the reform of Julius Caesar, it became the sixth month and received another day.

7. July, the seventh month

With the same reform mentioned above, the month that was originally the fifth in the calendar of Roman antiquity and was named became the seventh

8. August, the eighth month

In the ancient Roman calendar, this was the sixth month of the year; it became the eighth when the months of January and February were introduced.

9. September, the ninth month

It was originally the seventh month of the year and had 29 days until the Julian reform, when it became the ninth month and received another day.

10. October, the tenth month

In the Gregorian calendar, this is the tenth month. However, this was not always the case. In the ancient Roman calendar, which was only 10 months long, this month was the eighth.

11. November, the eleventh month

This was the ninth month in the ancient Roman calendar and became the eleventh after it was modified and added to January and February.

12. December, the twelfth month

It is now the twelfth month, but it was the tenth month in the calendar of Roman antiquity.

fun fact

Interesting fact

Until January and February were included in the calendar, the time interval from the end of December to the beginning of March was not included in any month. It was simply the winter period.

How many days are in a month?

As we know, not all months in the calendar have the same number of days. Some have 30, others 31, and there is also the month of February, which for three years in a row has 28 days, and in the fourth year, 29 days. Let's look at them one at a time.

Which months have 30 days?

Every year, four months have 30 days. These are:

  • April
  • June
  • September
  • November

Which months have 31 days?

Every year, seven months have 31 days. These are:

  • January
  • March
  • May
  • July
  • August
  • October
  • December

How many days does February have?

February, based on the number of days it has, is the month that makes the difference between a Common year and a Leap year.

February in a Common year

For three consecutive years, February has 28 days.

February in a Leap year

Once every four years, February has 29 days. This extra day is called Leap day.

What are the months of each season?

Depending on their location in the world, in some countries, January is a winter month, while it is a summer month in other countries. This is because the earth revolves in an elliptical orbit around the sun and because this happens on an inclined axis.

Consequently, depending on the position in front of the sun, different seasons are formed. This means that while at a certain time of the year in one part of the earth it is summer, in another part of the planet, at the same time, it is winter.

Thus, while in the Southern Hemisphere the earth is warmest in December, January, and February, in the Northern Hemisphere it is winter during this period.

  • Countries located in the Southern Hemisphere: Argentina, Australia, Bolivia, Brazil, Chile, New Zealand, Paraguay, Peru, South Africa, and Uruguay
  • Countries located in the Northern Hemisphere: United States, Austria, Belgium, Bulgaria, Canada, China, France, Germany, Hungary, India, Japan, Mexico, Netherlands, Norway, Poland, Romania, Russia, Spain, Sweden, Switzerland, United Kingdom, Ukraine

Spring months

In the Southern Hemisphere In the Northern Hemisphere
September March
October April
November May

Summer months

In the Southern Hemisphere In the Northern Hemisphere
December June
January July
February August

Autumn months

In the Southern Hemisphere In the Northern Hemisphere
March September
April October
May November

Winter months

In the Southern Hemisphere In the Northern Hemisphere
June December
July January
August February

Rainy season months

Monsoon rainy season Savannah rainy season Tropical rainy season
Indonesia, October - April Florida (USA), May - October Hawaii (USA), November - March
Thailand, May - October Ethiopia, June - September Mexico, June - September
Maldives, May - December Nigeria, April - October Peru, December - March
India, July - November Ghana, April - October The Philippines, all year-round

Dry season months

Northern Australia Amazon Region Equatorial & Southern Africa
August, September, October May to October (less rain) May, June, July, August

How many months in a school year

Generally speaking, a school year lasts between 9 and 10 months.

Specifically, the duration of a school year is about 180 school days. These run from August/September to May/June but are interspersed with holidays and various days off. Usually, the first semester is between August/September and December, and the second semester is between January and May/June.

Summer vacation usually includes the months of June, July, and August.

How many months in a quarter of a year (trimester)

A quarter of a year has exactly three months. A quarter means ¼ (one-fourth) of something. Because the year has 12 months, if we divide it by 4, we get four intervals of three months each. If we start from January, the following months will be included in each quarter of the year:

  • First quarter: January, February, March
  • Second quarter: April, May, June
  • Third quarter: July, August, September
  • Fourth quarter: October, November, December

How many months in a semester

The word "semester" comes from the Latin "semestris," which means "of six months." From this point of view, as the year has 12 months, it is clear that it is composed of two semesters.

Calendar semesters

If we start from January, the months included in each of the two semesters are:

  • First semester: January, February, March, April, May, June
  • Second semester: July, August, September, October, November, December

Academic semesters

From the point of view of the school year (academic), the semesters represent a planning system that breaks an academic year into two terms. The length of the school semester is variable and has nothing to do with the calendar semesters.

For example, for educational institutions that use the K-12 schedule, each semester is approximately 18 weeks long, while universities consider one semester to be from August/September to December and the other from January to May/June.

Other types of months [in astronomy]

A solar calendar, such as the Gregorian calendar used today, is one that takes into account the apparent position of the sun relative to the stars.

Apart from that, there is a lunar calendar, which is based on the monthly cycles of the moon. From this point of view, there are several types of lunar months. Most of them have been noticed since Babylonian lunar astronomy.

  • Sidereal month
  • Synodic month
  • Tropical month
  • Anomalistic month
  • Draconic month
fun fact

Fun fact about the months of the year

In 1793, France established its own calendar, which was used until 31 December 1805. The year also had 12 months, but they were made up of three weeks of 10 days each. The remaining five days were grouped at the end of the year as holidays.

The funny part is the satire created by an English poet (George Ellis, 1753-1815) for the creative names that the French gave to the months in their calendar. These names referred to the weather and the related crops.

Months of the year French republican calendar months George Ellis satirical version
January Pluviôse Flowy
February Ventôse Blowy
March Germinal Showery
April Floréal Flowery
May Prairial Bowery
June Messidor Hoppy
July Thermidor Croppy
August Fructidor Droppy
September Vendémiaire Breezy
October Brumaire Sneezy
November Frimaire Freezy
December Nivôse Snowy

Mariana Holostenco

Contributor at PlanArty

Economist with a degree in Marketing and International Economic Affairs. Mariana is passionate about efficient time management in business. Therefore, she shares with our readers and our team members her knowledge and experience in this domain.