Ruling on organizing prayers for rain if this is not done by the ruler
Question

                If the ruler of a state is neglecting the Sunnah of praying for rain (salaat al-istisqaa’), and he does not call the people to offer this prayer when there is no rain or the wells have dried up, is it permissible for the imaam of one of the mosques in that country to call the people of his city to offer the prayer for rain and for them to go out on their own to offer this prayer?
Praise be to Allah.If the people of a city are not ordered by their ruler to offer the 
          Eid prayers or prayers for rain, then it is prescribed for them to offer 
          the Eid prayer and prayers for rain in the desert (i.e., outside the 
          city) if that is possible, or else in the mosques, because the Messenger 
           (peace and blessings of Allaah 
          be upon him) prescribed that for his ummah. Eid prayer is fard kafaayah 
          (i.e., if some members of the community 
          undertake this duty, the rest are free from blame, but if no one does 
          it, all will be held to blame), so it is not permissible for the Muslims 
          in any city to neglect it. Some of the scholars said that it is fard 
          ‘ayn (an individual obligation) like Jumu’ah prayers, because the 
          Messenger of Allaah  (peace 
          and blessings of Allaah be upon him) did it and ordered others to do 
          it.