The month of Cheshvan is drawing to a close. This Shabbat, we will offer an elaborate blessing in anticipation of Rosh Chodesh Kislev (in which we will celebrate Chanukah). Of all the months of the Jewish year, Cheshvan and Kislev alone vary in length. They include either 29 or 30 days.
When both Cheshvan and Kislev are 30 days long, the year is termed Sheleimah – “full.” When both Cheshvan and Kislev are 29 days long, the year is termed Chaseirah – “defective or lacking.” And when the two months differ from each other in length (as they do this year: 29 days of Cheshvan; 30 days of Kislev), the year is called K’Sidrah – “ordinary.”
Among other complexities of the Jewish calendar, the variability of Cheshvan and Kislev helps assure that Yom Kippur never immediately precedes or follows Shabbat… avoiding two straight days of the most strident restrictions and prohibitions.
All other Jewish months are of a fixed duration: Tishrei, Shevat, Adar I in a leap year, Nisan, Sivan, and Av are 30 days long. Tevet, Adar (or Adar II in a leap year), Iyyar, Tammuz, and Elul last 29 days.
Rabbi Joseph H. Prouser is the rabbi of Temple Emanuel of North Jersey and the editor of “Masorti: The New Journal of Conservative Judaism.” The latest edition of Masorti was published online in December of 2024. A subscription is $18 per annum.
When both Cheshvan and Kislev are 30 days long, the year is termed Sheleimah – “full.” When both Cheshvan and Kislev are 29 days long, the year is termed Chaseirah – “defective or lacking.” And when the two months differ from each other in length (as they do this year: 29 days of Cheshvan; 30 days of Kislev), the year is called K’Sidrah – “ordinary.”