بسم الله الرحمن الرحيم
Q: Is the mere falling of rain considered an excuse to abandon the congregational prayer or is severe rain conditional for such?
A: Allah knows best but severity (heavy rains) is not conditional. If wetness occurs that is harmful to the praying person then this is an excuse from Allah’s mercy. Whenever there is slippery moisture and it is harmful regardless if it be lite rain, then this is an excuse.
Translated by Najeeb Al Anjelesi
Source: فتاوى فضيلة الشيخ العلامة ربيع بن هادي عمير المدخلي