فَقُلْتُ اسْتَغْفِرُوا رَبَّكُمْ إِنَّهُ كَانَ غَفَّارًا يُرْسِلِ السَّمَاءَ عَلَيْكُمْ مِدْرَارًا
Translation: I said, seek your Lord’s forgiveness, for He is ever Forgiving; He will send abundant rain upon you.
Surah Nuh 71:10–11 links seeking forgiveness with plentiful rain. Thus repentance and seeking forgiveness carry particular weight in istisqa.