Hebrew Calendar of the Old Testament

Hebrew Month	Canaanite Name	Modern Equivalent	Farm Season	Climate	Festivals
Nisan (Religious New Year)	Abib	March/April	Barley Harvest	Latter rains	14- Passover 21- First Fruits
Iyyar	Ziv	April/May	General Harvest	Latter rains
Sivan		May/June	Wheat Harvest Vine Dressing	Dry Season	6- Pentecost
Tammuz		June/July	Early Grape Harvest
Ab		July/August	Harvest: Grapes, Figs, Olives		9- Destruction of Temple
Elul		August/Sept	Summer Fruit
Tishri (Civil New Year)	Ethanim	Sept/October	Plowing, Olive Harvest		1- New Year 10- Atonement 15-21 Tabernacles
Marchesvan	Bul	Oct/Nov	Olive Harvest, Grain Planting	Early Rains
Chislev		Nov/Dec	Grain Planting	Early Rains	25- Dedication of Temple
Tebeth		Dec/January	Late Planting, Spring Growth	Rainy Season
Shebat		January/Feb	Late Planting, Winter Figs
Adar		Feb/March	Pulling Flax, Almonds Bloom
Adar Sheni (Second Adar)		Intercalate Month

The Lunar Calendar

The system of keeping time in the Old Testament was based on the cycles of the moon rather than a solar calendar like we use today. In fact, the Hebrew term for "month," chodesh, means "new [moon]," referring to the new moon that began the month. The lunar cycle played a significant role in the cultural and religious life in ancient Israel so that time could be counted by the cycles of the moon (Ex. 19:1). The New Moon was a festival day, observed by burnt offering and sacrifices as well as banquets (Num 29:6, 1 Sam 20:5, 1 Chron 23:31). The New Moon festival was often listed along with Sabbath as an important religious observance (2 Kings 4:23, Ezek 45:17). Like Sabbath and other rituals, it also came to symbolize empty and self-centered religion when not accompanied by faithfulness to God in other areas (Isa. 1:14, Amos 8:5). Likewise, the middle of the month or the Full Moon was an important marker of the passing of time. Two of Israel’s most important festivals fell in mid-month (Passover, Tabernacles; cf. Psa 81:3).

The Hebrew lunar calendar contained 12 months of 30 days, which was also the customary period of mourning (Deut 21:13, Num 20:29). Yet the actual lunar cycle is only about 29 � days, which resulted in a year of only 354 � days. Keeping the lunar calendar coordinated with the seasons of the year required adding a 13th month to the lunar calendar seven out of every nineteen years. This additional month was added to the end of the year following the last month Adar, and was simply called Second Adar.

Although the history of its development is not clear, the Israelites apparently adopted elements of marking time from both the ancient Canaanites and the Babylonians. Four months are known in the biblical text by older Canaanite names, while seven are mentioned in forms derived from Babylon. There are also preserved two New Years’ dates, one at the Spring equinox in the month of Nisan (Exod 12:1) and one at the Fall equinox in the month of Tishri (Exod 34:22). Some have suggested that this represents both a civil and a religious calendar, with the civil calendar adopted from the Babylonians during the exile and the religious calendar ordered around the events of the exodus. It may also represent a blending of elements of both lunar and solar time keeping. A tenth century BC inscription known as the Gezer Calendar begins in the Fall and lists the months according to what was harvested in that month.

Because of the differences between the solar and lunar systems of timekeeping, the Old Testament festivals that were linked to the New Moon fell at a general time, but the specific dates according to our solar calendar would vary. They are called movable feasts because of this variance. The Hebrew and later Jewish calendar established the time for the major festivals of the Old Testament. Since several of those Old Testament festivals figure prominently in the New Testament, the times they are observed were also adapted into Christian tradition. That explains why Easter (related to Old Testament Passover, since Holy Week occurred during the Passover Festival) and Pentecost (figured from the date of Passover) are movable feasts in Christian tradition; that is, they are calculated by the moon and not by the solar calendar, and so fall on different dates. The differences between Christian Easter and Jewish Passover are due to the development of different calendars during the last 2,000 years (see The Easter Season: Resurrection of the Lord).