اللَّهُمَّ اغْفِرْ لِي
Allahummagh-fir li (and any personal du'a)
O Allah, forgive me. (Du'a during rainfall is accepted.)
The Prophet ﷺ said that du'a is accepted at certain times, and one of them is during rainfall. Rain is a manifestation of Allah's mercy descending from the sky — and when mercy is descending, your requests ride up with it. Any personal du'a made while rain is falling carries extra weight. The scholars recommend not wasting a single rainy moment without lifting your hands.
Related Du'as
اللَّهُمَّ اجْعَلْهَا رَحْمَةً وَلَا تَجْعَلْهَا عَذَابًا
O Allah, make it a mercy and do not make it a punishment.
Hasanاللَّهُمَّ صَيِّبًا نَافِعًا
O Allah, let it be a beneficial rain.
Sahihاللَّهُمَّ إِنِّي أَسْأَلُكَ مِنْ خَيْرِ مَا سَأَلَكَ عَبْدُكَ وَنَبِيُّكَ مُحَمَّدٌ وَأَعُوذُ بِكَ مِنْ شَرِّ مَا اسْتَعَاذَ مِنْهُ عَبْدُكَ وَنَبِيُّكَ
O Allah, I ask You for the good that Your servant and Prophet Muhammad ﷺ asked You for, and I seek refuge in You from the evil that Your servant and Prophet sought refuge from.
Hasanاللَّهُمَّ إِنِّي أَسْأَلُكَ خَيْرَهَا وَخَيْرَ مَا فِيهَا وَخَيْرَ مَا أُرْسِلَتْ بِهِ وَأَعُوذُ بِكَ مِنْ شَرِّهَا وَشَرِّ مَا فِيهَا وَشَرِّ مَا أُرْسِلَتْ بِهِ
O Allah, I ask You for its good, the good within it, and the good it was sent with. And I seek refuge in You from its evil, the evil within it, and the evil it was sent with.
Sahih