In Eretz Yisrael we start saying V'Sain Tal U'Matar on the 7th of Cheshvan. If someone from Eretz Yisrael will be in America on the 7th of Cheshvan and will be flying back to Eretz Yisrael a few days after that what is the halacha in regards to when they should start saying V'Sain Tal U'Matar?
So too in the opposite case: when someone from America is in Eretz Yisrael on the 7th of Cheshvan but will be returning to America afterwards (before they begin to say there.) What is the halacha by this person?