Baltimore, MD - Dec. 3, 2019 - This year (5780/2019) in chutz la’aretz we will begin reciting vesein tal umotor livracha at Maariv of Thursday night, December 5th.  It is well known that in chutz la’aretz we usually begin saying vesein tal umotor livracha in Shemoneh Esrei at Maariv of December 4th. Why is this year and every four years different?

The Shulchan Aruch (Orach Chaim 117:1), based on the Gemara in Maseches Taanis (10a), says that in chutz la’aretz, we begin reciting vesein tal umotor on the 60th day of tekufas Tishrei. [Note: “Tekufos” are seasons.]

In the 20th and 21st centuries, Tekufas Tishrei always occurs on October 7th. If we count October 7th as Day #1, then December 5th is Day #60. The halachic day of December 5th begins the night before. Therefore, usually (in these centuries), vesein tal umotor begins December 4th at Maariv, which is the beginning of Day #60.

The tekufah of Tishrei occurs every 365.25 days. In 2016, it occurred on October 7th at 3 a.m. In 2017, it occurred 365 days and 6 hours later – on October 7th at 9 a.m. In 2018, it occurred on October 7th at 3 p.m. This year, 2019, it occurred on October 7th at 9 p.m. Indeed, every four years, the tekufah of Tishrei occurs at 9 p.m. on October 7th, which is halachically the next day. This year it was Erev Yom Kippur and Day #60 begins at Maariv of December 5th (since Erev Yom Kippur was Day #1, Day #60 this year is 8 Kislev, which begins Thursday night, December 5th).

How does vesein tal umotor livracha revert back to December 4th at Maariv? The “fourth year” in our discussion is the civil year preceding a civil leap year. Because the following year (e.g., 2020) is a civil leap year and there are 366 days, instead of the tekufah moving ahead to 3 a.m. October 8th, the tekufah will move back to 3 a.m. on October 7th. For example, because there will be a February 29, 2020, 365 days and 6 hours after 9 p.m. on October 7, 2019 will be 3 a.m., October 7, 2020. In a civil leap year, the 60th day will once again begin at Maariv of December 4th (because next year December 4th occurs on Friday, we will not begin vesein tal umotor livracha until December 5th at Maariv, however in 2021 and 2022 we will begin vesein tal umotor livracha at Maariv of December 4th). It is interesting to note that the Bais Yosef (Orach Chaim 117) based on the Avudraham discusses this issue and mentions the February 29th factor.

Every 100 years that is not divisible by 400 (e.g., 1800, 1900, 2100, 2200, etc.) is not a civil leap year, so vesein tal umotor moves ahead one day.

The following illustrates what will happen in the 22nd century. The tekufah in 2094 will be at 3 p.m. October 7th, so Day #60 begins at Maariv of December 4th. In 2095, the tekufah will be 365 days and 6 hours later, at 9 p.m. on October 7th, so vesein tal umotor will begin on December 5th at Maariv. Because there will be 366 days in the following year (i.e., there will be a February 29, 2096), 365 days and 6 hours later will be on October 7, 2096 at 3 a.m. and vesein tal umotor will once again begin on December 4 at Maariv. In 2097 and 2098, the tekufah will be on October 7th at 9 a.m. and 3 p.m. respectively. In 2099, vesein tal umotor will begin on December 5th at Maariv because the tekufah will occur at 9 p.m. on October 7th.

Since 2100 will not be a civil leap year (i.e., there will be no February 29, 2020), 365 days and 6 hours later will be at 3 a.m. October 8th. So, vesein tal umotor will begin on December 5th at Maariv (the beginning of Day #60). In 2101 and 2102, the tekufah will remain on October 8th at 9 a.m. and 3 p.m. respectively and vesein tal umotor will begin on December 5th at Maariv. In 2103, the tekufah will take place on October 8th at 9 p.m., so Day #60 begins at Maariv of December 6. It will then continue through the next century. In three out of every four years, it will begin at Maariv of December 5th, and in civil years that precede a civil leap year (i.e., 2103, 2107, etc.) at Maariv of October 6th (unless they are Friday nights). In short, vesein tal umotor shifts to December 5th and 6th in the next century because there will be no February 29, 2100.

For this century the rule is simple. In chutz la’aretz, Vesein tal umotor livracha begins on December 4th at Maariv, except in a civil year that precedes a civil leap year (2019, 2023, 2027, 2031, etc.) when it begins on December 5th at Maariv. Of course, if it is Friday night, vesein tal umotor livracha begins on Motzei Shabbos.

Rabbi Dovid Heber is the Rav of Khal Ahavas Yisroel Tzemach Tzedek in Baltimore and a Kashrus Administrator at Star-K. The above is based on his column Calendar Calculations that appears in Yated.