How Many Months in a Biblical Year?

According to the Bible there are 12 months (“chodesh”) in a year.

Now the children of Israel after their number, to wit, the heads of fathers’ houses and the captains of thousands and of hundreds, and their officers that served the king, in any matter of the courses which came in and went out month by month throughout all the months of the year – of every course were twenty and four thousand.
Over the first course for the first month was Jashobeam the son of Zabdiel: and in his course were twenty and four thousand. He was of the children of Perez, the chief of all the captains of the host for the first month.
And over the course of the second month was Dodai the Ahohite, and his course; and Mikloth the ruler: and in his course were twenty and four thousand.
The third captain of the host for the third month was Benaiah, the son of Jehoiada the priest, chief: and in his course were twenty and four thousand. This is that Benaiah, who was the mighty man of the thirty, and over the thirty: and of his course was Ammizabad his son.
The fourth captain for the fourth month was Asahel the brother of Joab, and Zebadiah his son after him: and in his course were twenty and four thousand.
The fifth captain for this fifth month was Shamhuth the Izrahite: and in his course were twenty and four thousand.
The sixth captain for the sixth month was Ira the son of Ikkesh the Tekoite: and in his course were twenty and four thousand.
The seventh captain for the seventh month was Helez the Pelonite, of the children of Ephraim: and in his course were twenty and four thousand.
The eighth captain for the eighth month was Sibbecai the Hushathite, of the Zerahites: and in his course were twenty and four thousand.
The ninth captain for the ninth month was Abiezer the Anathothite, of the Benjamites: and in his course were twenty and four thousand.
The tenth captain for the tenth month was Maharai the Netophathite, of the Zerahites: and in his course were twenty and four thousand.
The eleventh captain for the eleventh month was Benaiah the Pirathonite, of the children of Ephraim: and in his course were twenty and four thousand.
The twelfth captain for the twelfth month was Heldai the Netophathite, of Othniel: and in his course were twenty and four thousand.
(1Ch 27:1-15 ASV)

And Solomon had twelve officers over all Israel, who provided victuals for the king and his household: each man had to make provision for a month in the year.
(1Ki 4:7 ASV)

Now when the turn of every maiden was come to go in to king Ahasuerus, after that it had been done to her according to the law for the women twelve months (for so were the days of their purifications accomplished, to wit, six months with oil of myrrh, and six months with sweet odors and with the things for the purifying of the women),
(Est 2:12 ASV)

In the first month, which is the month Nisan, in the twelfth year of king Ahasuerus, they cast Pur, that is, the lot, before Haman from day to day, and from month to month, to the twelfth month, which is the month Adar.
(Est 3:7 ASV)

And he showed me a river of water of life, bright as crystal, proceeding out of the throne of God and of the Lamb, in the midst of the street thereof. And on this side of the river and on that was the tree of life, bearing twelve manner of fruits, yielding its fruit every month: and the leaves of the tree were for the healing of the nations.
(Rev 22:1-2 ASV)

What is interesting to note is that each and every month is addressed in the Tanakh.

1st Month (H7223 H2320)

Rear Up the Tabernacle
On the first day of the first month shalt thou rear up the tabernacle of the tent of meeting… And it came to pass in the first month in the second year, on the first day of the month, that the tabernacle was reared up. (Exo 40:2,17 ASV)

PASSOVER and the FEAST of UNLEAVENED BREAD
In the first month, on the fourteenth day of the month at even, is Jehovah’s passover. And on the fifteenth day of the same month is the feast of unleavened bread unto Jehovah: seven days ye shall eat unleavened bread. (Lev 23:5-6 ASV)

And Jehovah spake unto Moses in the wilderness of Sinai, in the first month of the second year after they were come out of the land of Egypt, saying, Moreover let the children of Israel keep the passover in its appointed season. (Num 9:1-2 ASV)

And in the first month, on the fourteenth day of the month, is Jehovah’s passover. And on the fifteenth day of this month shall be a feast: seven days shall unleavened bread be eaten. (Num 28:16-17 ASV)

Exodus from Egypt
And they journeyed from Rameses in the first month, on the fifteenth day of the first month; on the morrow after the passover the children of Israel went out with a high hand in the sight of all the Egyptians, while the Egyptians were burying all their first-born, whom Jehovah had smitten among them: upon their gods also Jehovah executed judgments. (Num 33:3-4 ASV)

Israelites come to Wilderness of Zin and Miriam dies there
And the children of Israel, even the whole congregation, came into the wilderness of Zin in the first month: and the people abode in Kadesh; and Miriam died there, and was buried there. (Num 20:1 ASV)

2nd Month (H8145 H2320)

Flood Begins
In the six hundredth year of Noah’s life, in the second month, on the seventeenth day of the month, on the same day were all the fountains of the great deep broken up, and the windows of heaven were opened. (Gen 7:11 ASV)

Earth is Dry after the Flood
And in the second month, on the seven and twentieth day of the month, was the earth dry. (Gen 8:14 ASV)

Israelites come to Wilderness of Sin and receive Manna and Quail
And they took their journey from Elim, and all the congregation of the children of Israel came unto the wilderness of Sin, which is between Elim and Sinai, on the fifteenth day of the second month after their departing out of the land of Egypt. (Exo 16:1 ASV)

Census Taken
And Jehovah spake unto Moses in the wilderness of Sinai, in the tent of meeting, on the first day of the second month, in the second year after they were come out of the land of Egypt, saying,… And they assembled all the congregation together on the first day of the second month; and they declared their pedigrees after their families, by their fathers’ houses, according to the number of the names, from twenty years old and upward, by their polls. (Num 1:1,18 ASV)

Makeup PASSOVER
In the second month on the fourteenth day at even they shall keep it; they shall eat it with unleavened bread and bitter herbs: (Num 9:11 ASV)

Israelites Leave Mt Sinai
And it came to pass in the second year, in the second month, on the twentieth day of the month, that the cloud was taken up from over the tabernacle of the testimony. (Num 10:11 ASV)

3rd Month (H7992 H2320)

Israelites come into the Wilderness of Sinai
In the third month after the children of Israel were gone forth out of the land of Egypt, the same day came they into the wilderness of Sinai. (Exo 19:1 ASV)

Asa’s Reform
So they gathered themselves together at Jerusalem in the third month, in the fifteenth year of the reign of Asa. (2Ch 15:10 ASV)

Contributions for Worship
In the third month they began to lay the foundation of the heaps, and finished them in the seventh month. (2Ch 31:7 ASV)

The King’s Edict on Behalf of the Jews
Then were the king’s scribes called at that time, in the third month Sivan, on the three and twentieth day thereof; and it was written according to all that Mordecai commanded unto the Jews, and to the satraps, and the governors and princes of the provinces which are from India unto Ethiopia, a hundred twenty and seven provinces, unto every province according to the writing thereof, and unto every people after their language, and to the Jews according to their writing, and according to their language. (Est 8:9 ASV)

4th Month (H7243 H2320)

The FALL of JERUSALEM
in the eleventh year of Zedekiah, in the fourth month, the ninth day of the month, a breach was made in the city,) (Jer 39:2 ASV)

In the fourth month, in the ninth day of the month, the famine was sore in the city, so that there was no bread for the people of the land. (Jer 52:6 ASV)

Ezekiel’s Vision of the Living Creatures and the Glory of God
Now it came to pass in the thirtieth year, in the fourth month, in the fifth day of the month, as I was among the captives by the river Chebar, that the heavens were opened, and I saw visions of God. (Eze 1:1 ASV)

5th Month (H2549 H2320)

Aaron Dies
And Aaron the priest went up into mount Hor at the commandment of Jehovah, and died there, in the fortieth year after the children of Israel were come out of the land of Egypt, in the fifth month, on the first day of the month. (Num 33:38 ASV)

The FALL of JERUSALEM
Now in the fifth month, on the seventh day of the month, which was the nineteenth year of king Nebuchadnezzar, king of Babylon, came Nebuzaradan the captain of the guard, a servant of the king of Babylon, unto Jerusalem. (2Ki 25:8 ASV)

It came also in the days of Jehoiakim the son of Josiah, king of Judah, unto the end of the eleventh year of Zedekiah, the son of Josiah, king of Judah, unto the carrying away of Jerusalem captive in the fifth month. (Jer 1:3 ASV)

Now in the fifth month, in the tenth day of the month, which was the nineteenth year of king Nebuchadrezzar, king of Babylon, came Nebuzaradan the captain of the guard, who stood before the king of Babylon, into Jerusalem: (Jer 52:12 ASV)

Ezra comes to Jerusalem
And he came to Jerusalem in the fifth month, which was in the seventh year of the king. For upon the first day of the first month began he to go up from Babylon; and on the first day of the fifth month came he to Jerusalem, according to the good hand of his God upon him. (Ezr 7:8-9 ASV)

The False Prophet Hananiah
And it came to pass the same year, in the beginning of the reign of Zedekiah king of Judah, in the fourth year, in the fifth month, that Hananiah the son of Azzur, the prophet, who was of Gibeon, spake unto me in the house of Jehovah, in the presence of the priests and of all the people, saying, (Jer 28:1 ASV)

Elders Inquire of YHVH
And it came to pass in the seventh year, in the fifth month, the tenth day of the month, that certain of the elders of Israel came to inquire of Jehovah, and sat before me. (Eze 20:1 ASV)

Justice and Mercy, Not Fasting
and to speak unto the priests of the house of Jehovah of hosts, and to the prophets, saying, Should I weep in the fifth month, separating myself, as I have done these so many years? (Zec 7:3 ASV)

6th Month (H8345 H2320)

Visions of Idolatry in the Temple
And it came to pass in the sixth year, in the sixth month, in the fifth day of the month, as I sat in my house, and the elders of Judah sat before me, that the hand of the Lord Jehovah fell there upon me. (Eze 8:1 ASV)

A Call to Build the House of YHVH
In the second year of Darius the king, in the sixth month, in the first day of the month, came the word of Jehovah by Haggai the prophet unto Zerubbabel the son of Shealtiel, governor of Judah, and to Joshua the son of Jehozadak, the high priest, saying, (Hag 1:1 ASV)

in the four and twentieth day of the month, in the sixth month, in the second year of Darius the king. (Hag 1:15 ASV)

7th Month (H7637 H2320)

Noah’s Ark rests
And the ark rested in the seventh month, on the seventeenth day of the month, upon the mountains of Ararat. (Gen 8:4 ASV)

Day of Shouting
Speak unto the children of Israel, saying, In the seventh month, on the first day of the month, shall be a solemn rest unto you, a memorial of blowing of trumpets, a holy convocation. (Lev 23:24 ASV)

And in the seventh month, on the first day of the month, ye shall have a holy convocation; ye shall do no servile work: it is a day of blowing of trumpets unto you. (Num 29:1 ASV)

Day of Atonement
And it shall be a statute for ever unto you: in the seventh month, on the tenth day of the month, ye shall afflict your souls, and shall do no manner of work, the home-born, or the stranger that sojourneth among you: for on this day shall atonement be made for you, to cleanse you; from all your sins shall ye be clean before Jehovah. (Lev 16:29-30 ASV)

Howbeit on the tenth day of this seventh month is the day of atonement: it shall be a holy convocation unto you, and ye shall afflict your souls; and ye shall offer an offering made by fire unto Jehovah. (Lev 23:27 ASV)

Then shalt thou send abroad the loud trumpet on the tenth day of the seventh month; in the day of atonement shall ye send abroad the trumpet throughout all your land. (Lev 25:9 ASV)

And on the tenth day of this seventh month ye shall have a holy convocation; and ye shall afflict your souls: ye shall do no manner of work; (Num 29:7 ASV)

FEAST of TABERNACLES
Speak unto the children of Israel, saying, On the fifteenth day of this seventh month is the feast of tabernacles for seven days unto Jehovah. (Lev 23:34 ASV)

Howbeit on the fifteenth day of the seventh month, when ye have gathered in the fruits of the land, ye shall keep the feast of Jehovah seven days: on the first day shall be a solemn rest, and on the eighth day shall be a solemn rest. (Lev 23:39 ASV)

And ye shall keep it a feast unto Jehovah seven days in the year: it is a statute for ever throughout your generations; ye shall keep it in the seventh month. (Lev 23:41 ASV)

And on the fifteenth day of the seventh month ye shall have a holy convocation; ye shall do no servile work, and ye shall keep a feast unto Jehovah seven days: (Num 29:12 ASV)

8th Month (H8066 H2320)

Solomon Builds the Temple
And in the eleventh year, in the month Bul, which is the eighth month, was the house finished throughout all the parts thereof, and according to all the fashion of it. So was he seven years in building it. (1Ki 6:38 ASV)

Golden Calves at Bethel and Dan
And Jeroboam ordained a feast in the eighth month, on the fifteenth day of the month, like unto the feast that is in Judah, and he went up unto the altar; so did he in Beth-el, sacrificing unto the calves that he had made: and he placed in Beth-el the priests of the high places that he had made. And he went up unto the altar which he had made in Beth-el on the fifteenth day in the eighth month, even in the month which he had devised of his own heart: and he ordained a feast for the children of Israel, and went up unto the altar, to burn incense. (1Ki 12:32-33 ASV)

A Call to Return to YHVH
In the eighth month, in the second year of Darius, came the word of Jehovah unto Zechariah the son of Berechiah, the son of Iddo, the prophet, saying, (Zec 1:1 ASV)

9th Month (H8672 H2320)

The People’s Confession of Sin
Then all the men of Judah and Benjamin gathered themselves together unto Jerusalem within the three days (it was the ninth month, on the twentieth day of the month); and all the people sat in the broad place before the house of God, trembling because of this matter, and for the great rain. (Ezr 10:9 ASV)

Jehoiakim Burns Jeremiah’s Scroll
Now it came to pass in the fifth year of Jehoiakim the son of Josiah, king of Judah, in the ninth month, that all the people in Jerusalem, and all the people that came from the cities of Judah unto Jerusalem, proclaimed a fast before Jehovah. (Jer 36:9 ASV)

Now the king was sitting in the winter-house in the ninth month: and there was a fire in the brazier burning before him. (Jer 36:22 ASV)

Justice and Mercy, Not Fasting
And it came to pass in the fourth year of king Darius, that the word of Jehovah came unto Zechariah in the fourth day of the ninth month, even in Chislev. (Zec 7:1 ASV)

10th Month (H6224 H2320)

Flood: Tops of the Mountains Seen
And the waters decreased continually until the tenth month: in the tenth month, on the first day of the month, were the tops of the mountains seen. (Gen 8:5 ASV)

The FALL of JERUSALEM
And it came to pass in the ninth year of his reign, in the tenth month, in the tenth day of the month, that Nebuchadnezzar king of Babylon came, he and all his army, against Jerusalem, and encamped against it; and they built forts against it round about. (2Ki 25:1 ASV)

And it came to pass when Jerusalem was taken, (in the ninth year of Zedekiah king of Judah, in the tenth month, came Nebuchadrezzar king of Babylon and all his army against Jerusalem, and besieged it; (Jer 39:1 ASV)

And it came to pass in the ninth year of his reign, in the tenth month, in the tenth day of the month, that Nebuchadrezzar king of Babylon came, he and all his army, against Jerusalem, and encamped against it; and they built forts against it round about. (Jer 52:4 ASV)

The People’s Confession of Sin
And the children of the captivity did so. And Ezra the priest, with certain heads of fathers’ houses, after their fathers’ houses, and all of them by their names, were set apart; and they sat down in the first day of the tenth month to examine the matter. (Ezr 10:16 ASV)

Esther Made Queen
So Esther was taken unto king Ahasuerus into his house royal in the tenth month, which is the month Tebeth, in the seventh year of his reign. (Est 2:16 ASV)

The Cooking Pot
Again, in the ninth year, in the tenth month, in the tenth day of the month, the word of Jehovah came unto me, saying, (Eze 24:1 ASV)

A Prophecy Against Egypt
In the tenth year, in the tenth month, in the twelfth day of the month, the word of Jehovah came unto me, saying, (Eze 29:1 ASV)

Jerusalem’s Fall Explained
And it came to pass in the twelfth year of our captivity, in the tenth month, in the fifth day of the month, that one that had escaped out of Jerusalem came unto me, saying, The city is smitten. (Eze 33:21 ASV)

11th Month (H6249 H6240 H2320)

Moses Speaks to the Next Generation
And it came to pass in the fortieth year, in the eleventh month, on the first day of the month, that Moses spake unto the children of Israel, according unto all that Jehovah had given him in commandment unto them; (Deu 1:3 ASV)

The Man Among the Myrtle Trees
Upon the four and twentieth day of the eleventh month, which is the month Shebat, in the second year of Darius, came the word of Jehovah unto Zechariah the son of Berechiah, the son of Iddo, the prophet, saying, (Zec 1:7 ASV)

12th Month (H8147 H6240 H2320)

Jehoiachin Restored
And it came to pass in the seven and thirtieth year of the captivity of Jehoiachin king of Judah, in the twelfth month, on the seven and twentieth day of the month, that Evil-merodach king of Babylon, in the year that he began to reign, did lift up the head of Jehoiachin king of Judah out of prison; (2Ki 25:27 ASV)

Haman’s Plot to Destroy the Jews
And letters were sent by posts into all the king’s provinces, to destroy, to slay, and to cause to perish, all Jews, both young and old, little children and women, in one day, even upon the thirteenth day of the twelfth month, which is the month Adar, and to take the spoil of them for a prey. (Est 3:13 ASV)

The King’s Edict in Behalf of the Jews
…upon one day in all the provinces of king Ahasuerus, namely, upon the thirteenth day of the twelfth month, which is the month Adar. (Est 8:12 ASV)

Triumph of the Jews
Now in the twelfth month, which is the month Adar, on the thirteenth day of the same, when the king’s commandment and his decree drew near to be put in execution, on the day that the enemies of the Jews hoped to have rule over them, (whereas it was turned to the contrary, that the Jews had rule over them that hated them), (Est 9:1 ASV)

Jehoiachin Released
And it came to pass in the seven and thirtieth year of the captivity of Jehoiachin king of Judah, in the twelfth month, in the five and twentieth day of the month, that Evil-merodach king of Babylon, in the first year of his reign, lifted up the head of Jehoiachin king of Judah, and brought him forth out of prison; (Jer 52:31 ASV)

A Lament for Pharaoh
And it came to pass in the twelfth year, in the twelfth month, in the first day of the month, that the word of Jehovah came unto me, saying, (Eze 32:1 ASV)

If Scripture only teaches there are 12 months (“chodesh”) in a year, where does the idea of a 13th month come in?