The Gemara in בבא בתרא 25b, discusses Israel’s climate and rainfall. When the Torah discusses the blessings that will come to the Jewish people, we are told that rains will come from אוצרו הטוב, from Hashem’s good treasure.
The Gemara goes on to explain that there is a big difference when Israel is fulfilling the will of G-d and they are dwelling in the land. When both of these things happen, that the Jewish people are living in the Land and fulfilling the will of Hashem, the good rains come.
It follows that even when the Torah is observed outside of Israel, but the Land is desolate of Jews, there will not be the same blessings.
It is clear that the ideal situation for the Jewish people is that they observe the Torah and live in Eretz Yisrael. When this happens, we will merit Hashem’s blessings. We will then fulfilling the ultimate purpose of the Jewish people.