Our Sages enacted that one must request dew and rain from Hashem during the rainy season in the “Blessing of the Years” found in the Amida prayer (ninth blessing of the Amida). In Israel, we begin requesting rain from the night of the Seventh of Marcheshvan. This year (5772), the night of the Seventh of Marcheshvan falls out on this coming Thursday night, i.e. during the Arvit prayer of this coming Thursday night, one should begin reciting “Barech Alenu” and “Ve’Ten Tal U’Matar Livracha.” “The Blessing of the Years” is a blessing which includes mankind’s collective need to be showered with abundance from Heaven. Included in this blessing is a prayer for one’s livelihood and that blessing rest in all that we do.
The Reason We do not Request Rain Beginning from Simchat Torah
Although it seems that we should have begun requesting rain immediately following the holiday of Sukkot since we enter the season worthy of rainfall at that point (it is for this reason that we indeed begin reciting the “Powers of Rain,” i.e. “Mashiv Ha’Ruach U’Morid Ha’Geshem” from the Mussaf prayer of Simchat Torah [Shemini Atzeret outside of Israel]), nevertheless, our Sages enacted that one should not request rain in the “Blessing of the Years” until the night of the Seventh of Marcheshvan, for the entire Jewish nation would make a pilgrimage to the Bet Hamikdash during the Sukkot holiday and would then head home; since it took certain people until the Seventh of Marcheshvan to arrive home, in order for those making the pilgrimage not to be harmed by the rain, our Sages established to abstain from asking for rain until the Seventh of Marcheshvan.
“The Blessing of the Years” Outside of Israel
Outside of Israel, we begin requesting dew and rain in the “Blessing of the Years” beginning from the Arvit prayer of the Fourth of December. In a year during which February has twenty-nine days (such as this coming year), we begin asking for dew and rain beginning from the Arvit prayer of the Fifth of December. This is indeed the custom in Europe and in the United States.
In countries where the climate is the opposite of Israel and Europe, i.e. their summer is between Sukkot and Pesach, they do not request dew and rain in the “Blessing of the Years” and they do not mention “Mashiv Ha’Ruach U’Morid Ha’Geshem” in the “Ata Gibor” blessing of the Amida. During their winter, they should request dew and rain within the “Shema Koleinu” blessing of the Amida.
In countries with seasons opposite of those in Israel, such as Argentina and Brazil, the Halacha for such countries follows the ruling prescribed by the Sefer Halacha Berura that they have the same law as those in the United States and must request dew and rain from the Fourth or Fifth of December. This is indeed the opinion of the consensus of great Poskim.
Taking Care not To Err While Reciting the “Blessing of the Years” or “Mashiv Ha’Ruach”
One should take care not to continue his recitation of the “Blessing of the Years” during the winter months as he has during the summer months, for besides for resulting in the prohibition of reciting blessings in vain, this also shows an overall levity towards one’s prayer, as he shows that he is not even paying attention to the words emerging from his mouth. The same applies to the recitation of “Mashiv Ha’Ruach U’Morid Ha’Geshem,” for although we have already established that if one mistakenly said “Morid Ha’Tal” instead of “Mashiv Ha’Ruach” as he was accustomed to during the summer months, he does not repeat the Amida prayer, nevertheless, the Mekubalim write that this causes a great deficiency in one’s prayer. (See Chemdat Yamim, Shemini Atzeret, for more on this matter.) With some minor attentiveness, one can prevent all of these errors.