This Motzaei Shabbos, December 4th at Maariv, we begin saying V’sain Tal U’matar in Bareich Aleinu.
If one forgets V’sain Tal U’matar, he can make it up by saying it in Shema Koleinu. However, once past Shema Koleinu, one must go back to Bareich Aleinu. If one has already finished Shemoneh Esrei, he must repeat the Tefillah.
If one is unsure what he said, until 30 days have passed, we assume that he did not say V’sain Tal U’matar. However, one who says 90 times (ideally 101 times) “V’es Kol…V’sein Tal U’matar” may thereafter be halachically presumed to have said it properly and thus will need not repeat if unsure.
