The Prophet Sallallahu Alayhi Wa Sallam was such that if he would see a collection of clouds starting to form in the horizon he would leave work, even if he was in the middle of supplication, then he would say:
Allãhumma ‘innee ‘a`outhu bika min sharrihã
“O my ‘ilãh I solicit Your protection from its evil.
Then if it would rain, he would say:
‘Allãhumma sayyiban hanee’an
“O my ‘ilãh make it go straight to the target, and make it a means for our well-being.