In the middle of the 9th blessing of the weekday Amidah, we read the blessing of the year. In the middle of it, there is a rather cryptic message about a change of text. It says, “From Passover to December 3rd, add the words “Grant blessing”. From December 4th to Passover, add the words “Grant dew and rain for blessing.”
A number of questions quickly arise. Why the text change? What does Passover have to do with it? Why December 3rd/4th? And why a Gregorian calendar date, instead of a Jewish calendar date?
So, in order:
  1. There is a textual change in response to atmospheric conditions in Israel. Unlike the U.S., when it can rain in any season, Israel has only two seasons—a dry season that lasts for six months, and a rainy season that lasts for six months.
  2. The dry season starts on Passover. It lasts for six months until Shemini Atzeret (when we say Geshem, the prayer for rain).
  3. But that only deepens the question, “Why December 3rd/4th?” The answer has to do with the holiday of Sukkot, the most widely celebrated holiday in ancient Israel. After Sukkot, the hundreds of thousands of pilgrims who had come to Jerusalem had to return home. Out of consideration to them, people in Israel didn’t start actively saying a prayer for rain until 7 Cheshvan, 2 weeks after Shemini Atzeret. Pilgrims from the Diaspora, on the other hand, needed more time to get home. As a result, the rabbis suggested waiting 60 days after the autumnal equinox (Sept. 21) before Diaspora communities started prayer for rain.
  4. The fact that the start date was related to the solar calendar (Sept. 21) meant that the 60 day period was tracked by the solar calendar.
But wait, there’s more. 60 days after Sept. 21 is Nov. 21. So why are we waiting until December 3rd/4rd? Here it gets really tricky, so hang in there. There is a slippage between the solar (secular Gregorian) calendar and the lunar (Jewish) calendar of about 11 minutes and 14 seconds. The Hebrew date for November 21, 500 CE would shift slightly every year, until reaching November 22, 628 CE. And then November 23, 756, etc. Leading us to our current situation. And soon enough, newer prayerbooks will list December 4th/December 5th as the appropriate starting dates.
So now for the really important question: Who cares? Or less cheeky, why does all this matter? For at least two reasons:
  1. There is such a thing as a beracha l’vatalah—a blessing in vain. You don’t make blessings for things that can’t happen. You don’t say hamotzi if there is no bread. You don’t pray for rain if there’s no rain—and there really, really, isn’t any rain in Israel between Passover and Shemini Atzeret. Seriously.
  2. Equally important, it behooves us to remember that when we pray (for rain and for anything else), we are not praying in the abstract for something that happens in the abstract. We don’t pray for “rain somewhere on earth.” We pray for something that happens in some very particular place, the Land of Israel. Every time we say this prayer, in other words, we become tethered to the fate of our people as a collective whole in our spiritual homeland. From Gothenburg, Sweden to Johannesburg, South Africa, from Winnepeg, Canada to Tierra Del Fuego, Argentina—all Jews everywhere pray for the well-being of the Land of Israel.
Ten Tal Umatar
Recited from evening of December 4 until Passover.
Unusual [Why?] Since it is the only date in the lunar Jewish calendar explicitly linked to a set date on the solar calendar.
Commonly explained that this date is set as 2 months after the autumnal equinox.
Reason was to allow the pilgrims in Jerusalem for sukkot (the biggest pilgrimage holiday) a full two months to return to their homes before the rains began (remember that although it can rain in Israel as early as the end of September, the real heavy rains don’t generally start until December.
[What’s wrong with this picture?] 60 days before December 5 is October 6. But the autumnal equinox is September 22!
How do we explain a 15 day difference?
Difference can be explained this way. The determination of when the equinoxes and solstices fall was made by Rabbi Shmuel Yarchinai in the 2nd century CE. According to his theory, the length of the solar year was 365 days and 6 hours. [A more exact calculation was made by Rabbi Adda, of 365 days, 5 hours, 55 minutes and 25.438 seconds. Unfortunately, it was too complicated to be used easily. In addition, up until the 16th century the figure of 365 and ¼ days was commonly used in non-Hebrew solar calendar systems].
The problem with Rabbi Shmuel’s calculation is that it differs from the astronomical reality by 11 minutes, 13.931 seconds. What that means is that for each year that passes, the rabbinic calculation for the autumnal equinox comes more than 11 minutes later than the actual equinox.
This may not seem like much. But every five years it comes an hour later. Every fifty years it comes ten hours later. Every century it comes almost a day later than in the previous century. Indeed, in the 1800’s, 60 days after the rabbinic equinox (tekufah) was December 4, not Dec 5. In the 1700’s, December 3. In the 16 and 1500’s, December 2.
Starting from October 5, and counting back slightly less than one day per century, (actually, roughly 5 days per six centuries) we will see that 18 centuries ago, in the time of Rabbi Samuel, he based his calculation on the correct perception that the autumnal equinox falls on September 22. So he originally had people start saying Ten Tal u’matar on November 21—and that date has been progressing forward ever since.