Sivan
Sivan is the third month of the Hebrew calendar, counting from Nisan in the ecclesiastical reckoning, typically corresponding to late May or early June on the Gregorian calendar and comprising 30 days.[1][2]
The month holds central significance in Jewish tradition as the time when the Israelites arrived at Mount Sinai and received the Torah from God on the sixth of Sivan, an event commemorated annually by the festival of Shavuot, also known as the Feast of Weeks or Pentecost.[3][4]
Biblically, Sivan is referenced as the "third month" in Exodus 19:1, marking the encampment at Sinai, while its name appears explicitly in the Book of Esther 8:9, denoting the issuance of a royal decree.[5][3]
Shavuot, observed on the 6th and 7th of Sivan (or 6th in Israel), celebrates not only the revelation at Sinai but also the wheat harvest and the offering of the first fruits (bikkurim) in the Temple, underscoring themes of divine instruction, agricultural bounty, and covenantal renewal.[2][6]
Calendar Position and Characteristics
Numerical and Seasonal Placement
Sivan serves as the third month in the ecclesiastical Hebrew lunisolar calendar, which counts from Nisan as the first month, a sequence rooted in biblical precedent and formalized in post-Exilic Jewish tradition under Babylonian influence.[5][1] This positioning places Sivan immediately after Iyar (the second month, with 29 days) and before Tammuz (the fourth month, with 29 days), with Sivan itself fixed at 30 days in length as determined by rabbinic calculations to align lunar cycles with solar years.[2][7] In the Northern Hemisphere, particularly in the region of ancient Israel, Sivan corresponds to late spring transitioning into early summer, typically spanning late May to early June on the Gregorian calendar.[5] This seasonal window follows the barley harvest, which ripens earlier in spring during Nisan and Iyar, and precedes or coincides with the initial stages of the wheat harvest, reflecting the agricultural realities of the Levant where grains mature progressively from barley to wheat under Mediterranean climate patterns.[8][9] The Hebrew calendar's intercalation mechanism—adding an extra Adar (Adar II) in seven years of a 19-year Metonic cycle—prevents drift from solar seasons, ensuring Sivan consistently precedes the height of summer and maintains synchrony with these harvest phases without reliance on contemporary astronomical observations or adjustments.[10][11] This fixed arithmetic system, codified around the 4th century CE, preserves the empirical alignment of lunar months with equinoctial and agricultural markers observed historically.[12]Correspondence to Civil Calendars
The Hebrew month of Sivan typically spans from late May to late June in the Gregorian calendar, encompassing approximately 30 days aligned with the lunar cycle.[7][13] This positioning results from the lunisolar structure of the Hebrew calendar, where months follow the moon's phases while leap months (added seven times in a 19-year Metonic cycle) prevent seasonal drift against the solar year of about 365.25 days.[14] Exact Gregorian equivalents for Sivan vary yearly due to these intercalations and the calculation of the molad—the mean conjunction of the moon and sun, occurring roughly every 29 days, 12 hours, and 793 parts (where a part is 1/1080 of an hour).[11] For instance, in Hebrew year 5785 (corresponding to 2024–2025 CE), Sivan 1 commences at sunset on May 27, 2025, making Rosh Chodesh Sivan fall on May 28 Gregorian.[15][16] In contrast, for 5786 (2025–2026 CE), Sivan 1 aligns with May 16–17, 2026, illustrating the one- to two-week fluctuation possible across non-leap years.[17] The fixed calendar, standardized by Hillel II circa 359 CE to replace variable eyewitness sightings of the new crescent moon, incorporates four dechiyot (postponement) rules applied to Rosh Hashanah (Tishri 1), which cascade forward to determine Sivan's start and avoid undesirable weekday alignments for festivals.[11] These include deferring Tishri 1 if the molad falls after noon, on a Sunday (to prevent Hoshanah Rabbah on Sunday), Wednesday (to avoid Yom Kippur on Friday or Sunday), or if postponing to Thursday would follow a year where Hoshanah Rabbah was Friday—ensuring, for example, that Shavuot (Sivan 6–7) rarely falls adjacent to Shabbat in ways complicating grain offerings.[14][18] Such mathematical precision supplanted earlier empirical methods, which relied on Sanhedrin-declared new moons based on two witnesses' testimonies, providing verifiable consistency despite lacking direct solar bias.[11]Astronomical and Agricultural Features
Sivan spans a full lunar month of 30 days in the Hebrew lunisolar calendar, beginning at the sunset following the sighting of the new moon's first crescent, which approximates the synodic month of 29.53 days.[19][5][2] This fixed length ensures alignment with observable moon phases, from waxing crescent to the subsequent new moon, while the overall calendar intercalates months to synchronize with the solar year of approximately 365.25 days.[20] In astronomical terms, Sivan typically commences in late May or early June on the Gregorian calendar, positioning it amid the sun's progression through the Gemini zodiac constellation in sidereal terms.[5] Agriculturally, Sivan coincides with the maturation and harvest of wheat in the ancient Near Eastern climate of the Levant, where this grain served as a primary staple following the earlier barley harvest.[21][8] Wheat ripening depends on cumulative spring rainfall and rising temperatures, with the period's diurnal heat aiding in grain drying and threshing processes critical to pre-industrial farming.[21] Empirical records from the region indicate average daytime highs of 25–27°C in late May escalating to 29–33°C by mid-June, conditions that historically supported outdoor labor-intensive harvesting without excessive humidity interference.[22][23] These patterns reflect causal dependencies on Mediterranean seasonal shifts, where post-winter precipitation totals enable wheat yields sufficient for sustaining populations through summer scarcity.[8]