Just as in other parts of the ancient Near East, the Israelites developed a calendar based on the annual movement of the sun and the lunar cycle. The year was divided into twelve months, based on the observation that the lunar cycle repeats itself twelve times over the course of a year. The lunar year is approximately eleven days shorter than the solar year, so the Israelites periodically added an extra month to their calendar to ensure that all their festivals fell at the expected times in accordance with weather patterns (seasons) and agricultural cycles (sowing and harvesting).

In the early stages of Israel’s history, the year began in the seventh month (around the time of the autumn harvest). Later on, the year began in spring, in the first month following the day on which day and night are of equal length (which occurs once or twice a year).

However, time was more often measured by the seasons than by the names of the months. The year was divided into the dry season (April–September) and the rainy season (October–March). It was then further divided into the wheat-sowing season (November–December) and the harvest season (April–June). Time is also measured by agricultural activities carried out during specific months. For example, wheat is harvested in March and April, grapes are harvested in June and July, and summer fruit is picked in August and September.

The months themselves hold significant religious meaning for the Israelites. The beginning of each month (when the moon is still ‘new’) is considered a holy time, and the Feast of the New Moon is observed (Num. 28:11–15). Most of the annual festivals have traditional links to agricultural activities, as well as to events in Jewish history that they commemorate.

Autumn festivals:

The Feast of Trumpets (Rosh Hashanah, the first day of Tishri, the seventh month), a day to celebrate the new year and to remember the covenant God made with the Israelites at Sinai, this festival marks the beginning of the annual festivals (Lev. 23:23–25; Num. 29:2–6).

The Feast of Atonement (Yom Kippur, the tenth day of Tishri), a day when the people express their sorrow for their sins through fasting and the priest purifies the Holy of Holies by sacrificing a bull for himself and a male goat for the sins of the people. A second male goat (known as the ‘scapegoat’) is sent into the wilderness to symbolise the people’s sins being cast away (Lev. 16:1–34; Deut. 29:7–11).

The Feast of Tabernacles (Sukkoth, the fifteenth day of Tishri) A week-long celebration commemorating the people’s forty-year wanderings in the wilderness before entering the Promised Land (Lev. 23:33–43).

The Festival of Dedication (Hanukkah, the twenty-fifth day of Kislev) A week-long celebration commemorating the rededication of the Temple by Judas Maccabeus in 164 BC. The story of Judas and his brothers is recounted in the First Book of Maccabees, which details events in Jewish history from 175–134 BC (1 Maccabees 4:36–59; John 10:22)

Spring Festivals:

Passover and the Feast of Unleavened Bread (the fifteenth day of Nisan) A week-long festival commemorating God’s deliverance of the Israelites from slavery in Egypt and giving thanks for the harvest and livestock (Ex. 12:23–25).

The Feast of Pentecost (Shavuoth, the sixth day of Sivan) A day to celebrate the wheat harvest and the beginning of the season when the first fruits are offered. It is also a day to remember how God delivered them from Egypt and provided a land that would ensure their livelihood (Lev. 23:15–21; Deut. 16:9–12).

The Feast of Purim (the thirteenth day of Adar) A day to celebrate how Queen Esther helped thwart Haman’s plot against the Jews during the reign of King Ahasuerus of Persia (Esther 9:20–32).

Source: Study Edition Bible