1)    In those areas where rain is needed in the summer period, the people living there should not ask for it in the blessing of “Bareich Aleinu”, as this would cause damage for the rest of the world. Instead, they should ask for it in the blessing of “Shome’a Tefillah”. (Shulchan Aruch O”Ch 117)

2)    However, one who erred in those places where they need rain in the summer period and said “Vesein Tal Umatar Livrachah” in the summer, does not need to return and repeat. If he wants, he may say an entire new Amidah as a voluntary prayer. (ibid)