Parashas Eikev · Passuk 11:12
It is a land that the ETERNAL your God looks after, on which the ETERNAL your God always keeps an eye, from year’s beginning to year’s end.
Torah Temimah points to Rosh Hashanah 17b.
TT lemma: עיני ה' אלהיך בה (unit 1 of 4).
English: “The eyes of Hashem your God are always upon it.” At times for good and at times for ill. For good: Israel was liable on Rosh Hashanah and little rain was decreed; they repented — one cannot increase it because the decree was already issued, but it falls at its proper time. For ill: Israel was meritorious on Rosh Hashanah and abundant rain was decreed; they later sinned — one cannot reduce it because the decree was already issued, but it falls at an improper time.
Custom (eyes of God — timing vs. quantity of rain)
Teshuvah after the decree can change the timing of rain when the quantity is fixed; the Land’s climate is watched continuously.