|Bible Month||Length||Roman Calendar Equivalent|
|1. Nisan||30 days||March-April|
|2. Iyar||29 days||April-May|
|3. Sivan||30 days||May-June|
|4. Tammuz||29 days||June-July|
|5. Av||30 days||July-August|
|6. Elul||29 days||August-September|
|7. Tishri||30 days||September-October|
|8. Cheshvan||29 or 30 days||October-November|
|9. Kislev||30 or 29 days||November-December|
|10. Tevet||29 days||December-January|
|11. Shevat||30 days||January-February|
|12. Adar||29 or 30 days||February-March|
|13. Adar II||29 days||March-April|
In the fourth century, a fixed calendar was developed by Jewish scholars to compensate for the fact that there are 12.4 lunar months in a solar year. The new version, used right to modern times, standardized the calendar for the course of a 19 year cycle, so that it meshes perfectly with the seasons. To do this, certain months had a set variable number of days, and a 13th month, Adar II, was added in the 3rd, 6th, 8th, 11th, 14th, 17th and 19th years of the cycle. Although its rules can seem complicated, it is actually a very simple system of having a perfectly natural calendar.
Fact Finder: At the time of Creation, what did God say about how to mark days, months, and seasons?