113. Morid HaTal

19:3 In locations where people say “morid hatal” in the summer months, if someone erred and said “tal” instead of “geshem” in the winter months, here’s how to proceed: If he remembers after he has already said “Baruch Atah Hashem,” he finishes saying the bracha. In this case, he does not have to repeat Shemoneh Esrei because he mentioned dew, if not rain. (Actually, this is true even if one mentioned dew in a location where people don’t say morid hatal – see OC 114:5.) However, if he remembered before saying God’s Name, he should say mashiv haruach in-between topics of the blessing.

19:4 If someone said mashiv haruach in the summer months (when he wasn’t supposed to), if he realized his error before completing the blessing, he goes back to the start of that bracha and says it again, properly. This is not because he needs to repeat the blessing per se; it’s because he needs to distinguish the erroneous bracha from the corrected one. However, if he only realized his mistake after he has finished the bracha, he must return to the beginning and start Shemoneh Esrei all over. If a person only said the words “mashiv haruach” but not “u’morid hageshem,” it is not problematic. And he can continue the bracha as per usual. If one accidentally said mashiv haruach on Shemini Atzeres – maariv or shacharis – there is no need to repeat Shemoneh Esrei.