Leap Day – Leap Month – Leap Year. What’s It All About?

Tevet 20, 5784; from sunset December 31, 2023, to sunset January 1, 2024

Leap Day? Leap Month? Leap Year? What’s it all about?

Today is the first day of 2024 per the Gregorian calendar. 2024 is a leap year and, it just so happens, the year 5784 on the Hebrew calendar is also a leap year. So, what’s the difference between the two?

Most of the world follows the Gregorian calendar. It was instituted by Pope Gregory XIII in 1582 AD and gradually adopted outside of the Roman Catholic sphere of influence. Before this, most people in the Roman Empire used the Julian calendar which was proposed by Julius Caesar in 46 BC. The Gregorian calendar is based solely on the solar cycle. As a comparison, the Islamic calendar is based solely upon the lunar cycle. The biblical calendar, however, uses a combination of both the lunar and solar cycles.

The Gregorian calendar fixed a small flaw in the Julian calendar by reducing the average length of the year from 365.25 days to 365.2425 days. This may seem like a minor issue, but it resulted in about a one day difference per century. Over the course of more than a thousand years, it caused the date of the spring equinox to drift away from the March 21st date we’re familiar with today. This posed a problem with the church’s calculation for Easter.

Most of us are familiar with the meaning of a leap year. It’s the one year out of four when an extra day – a leap day – is added to our calendars in order to remain in sync with the solar year. The solar year is roughly 365 ¼ days long. With our calendars measuring just 365 days, we need to make up that ¼ of a day every four years – making that fourth year 366 days instead. This extra day is added to the month of February, our shortest month, and is known as a leap day. The technical term is an “intercalary” day. There are also leap years on the biblical calendar. However, instead of a leap day, there is a leap month. The technical term, again, is an “intercalary” month. Intercalary is a term used for a day or a month which is inserted in order to put a calendar back into sync with the solar year.

In the Bible, the measurement of a month is determined by the lunar cycle. The lunar month is roughly 29 ½ days long. This means that, generally, if one biblical month is 29 days long, then the next month will be 30 days long. No matter how we do the math, twelve 29- or 30-day months will not add up to 365 ¼ days. A twelve-month biblical year ends up being about 354 days. So how does that work? Seven times out of a nineteen year cycle, an extra month is added to the biblical calendar. The twelfth month of the year (Adar) is doubled. They become known as Adar I and Adar II.

When God brought the children of Israel out of Egypt, He commanded Moses to make that month the first month of the year. It’s considered to be the first commandment that God gave to Israel as a nation.

Now the LORD spoke to Moses and Aaron in the land of Egypt, saying, “This month shall be your beginning of months; it shall be the first month of the year to you.” – Exodus 12:1-2 (NKJ)

He stipulated that it was to be the month of Abib…that is, the month when the barley is ripe. It was important to God to keep the calendar in sync with the harvest. This is mentioned in several places in the Bible.

And Moses said to the people: “Remember this day in which you went out of Egypt, out of the house of bondage; for by strength of hand the LORD brought you out of this place. No leavened bread shall be eaten. On this day you are going out, in the month Abib.” – Exodus 13:3-4 (NKJ)

“You shall keep the Feast of Unleavened Bread (you shall eat unleavened bread seven days, as I commanded you, at the time appointed in the month of Abib, for in it you came out of Egypt; none shall appear before Me empty); and the Feast of Harvest, the firstfruits of your labors which you have sown in the field; and the Feast of Ingathering at the end of the year, when you have gathered in the fruit of your labors from the field. – Exodus 23:15-16 (NKJ)

“The Feast of Unleavened Bread you shall keep. Seven days you shall eat unleavened bread, as I commanded you, in the appointed time of the month of Abib; for in the month of Abib you came out from Egypt. – Exodus 34:18 (NKJ)

“Observe the month of Abib, and keep the Passover to the LORD your God, for in the month of Abib the LORD your God brought you out of Egypt by night. – Deuteronomy 16:1 (NKJ)

So, what does this mean for the Today in the Bible blog, where our focus has been on placing biblical events on today’s calendar? When there is an event in the Bible which occurs in the twelfth month (Adar), it doesn’t call out whether it’s a regular year or a leap year. In this circumstance, most Hebrew calendars list the event on Adar II. That leaves the whole of Adar I without calendar listings. Since that is the case for this year, we will use the extra month to recognize the teachings of Moses that have become known as the book of Deuteronomy.

Deuteronomy 1:3 informs us that “Moses spoke to the children of Israel according to all that the LORD had given him as commandments to them.” He began teaching them on the first day of the eleventh month (Shevat). Tradition holds that he finished up the day he died, that is Adar 7. The month of Shevat will begin next week. Starting then, we’ll spend the next two months, Shevat and Adar I, working our way through the book of Deuteronomy. Then, on Adar II, we’ll resume the regular calendar entries.

We hope you’ll stick with us as we study through the all-important book of Deuteronomy. The repetition of the Law.