The number of days in each month varies. This list suggests the number of days typically found in each month yet is not conclusive.
Nissan 1 is the head of the year. It occurs at the sighting of the new moon (first sliver crescent) after Barley ripens in the Aviv (pronounced “Aveev”) season or literally when the Barley is in the Aviv stage.
Month 1 Ha Aviv / Nissan, Est. 3:7 – ha Aviv, Exodus 12:2 and Exodus 13:4 – in English, scripture calls it Abib (pronounced Aveev).
March – April
Month 2 Ziv – 1 Kings 6:1 calls it Zif – Not called Iyyar as Judaism states
April – May
Month 3 Sivan – Esther 8:9
30 Days
May – June
Month 4 No name – Tammuz is Not the name of the 4th month as Judaism states – That is a false God
June – July
Month 5 No name – Av is Not in the bible – This is Not the name of the 5th month as Judaism states
July – August
Month 6 Elul is the name of the 6th month Elul, seems like it is the name of the sixth month by the two verses below: Neh.6 [15] So the wall was finished in the twenty and fifth day of the month Elul, in fifty and two days. Neh.7[73] So the priests, and the Levites, and the porters, and the singers, and some of the people, and the Nethinims, and all Israel, dwelt in their cities; and when the seventh month came, the children of Israel were in their cities.
August – September
Month 7 Ha Ethanim – 1 Kings 8:2 – calls it Ethanim – Tishrei is the wrong name as Judaism states
September – October
Month 8 Bul – 1 Kings 6:38 – In English, scripture calls it Bul – Not called Cheshvan or Mar Cheshvan as Judaism states
October – November
Month 9 Chislev (Kislev) – Zach 7:1 – in English, scripture calls it Chisleu
November – December
Month 10 Teveth – Esther 2:16 – in English, scripture calls it Tebeth
December – January
Month 11 Shevat – Zechariah 1:7 – in English, scripture calls it Sebat
January – February
Month 12 (Adar I – leap years only)
February – March
Month 13 (Adar II – in leap years)
February – March
During a Jewish leap year, an extra month is added after the month of Shevat and before the month of Adar. It is called Adar Aleph, Adar Rishon, or Adar I. The month of Adar is then referred to as Adar Bet, Adar Sheni, or Adar II. A leap year occurs 7 times during the 19-year Metonic cycle, namely, in years 3, 6, 8, 11, 14, 17, and 19 of the cycle. What this means is that a leap month is added every 2 to 3 years.
The Metonic cycle is also known as Enneadecaeteris which is a period that comes very close to being a common multiple of the solar year and the lunar month (synodic month). With a deviation of just a few hours, 19 solar years have very nearly the same length as 235 lunar months, both periods amount to 6940 days.
This makes it possible for Jewish time reckoning to approximately stay in synchronization with the solar year simply by adding a certain amount of full months per Metonic cycle. Since 19 years with 12 months add up to 228 months, 7 extra months must be added to arrive at a total of 235 months per cycle.