"Dear god, I am asking that you alter the natural state of global weather patterns and focus precipitation in my local area. I am praying to you, oh lord, for rain. I ask this in your name, Jesus Christ, Amen."
First of all, if there was a god in charge of making things meteorologically happen, to produce weather at will, then it would be justifiable to blame the sky daddy solely for tornadoes, hurricanes and floods. In fact, it would be within our rights to be really pissed off about it. If I thought a omnipresent being was controlling the weather, I'd be saying "What the $%*# is wrong with you, A-hole, causing all this damage and loss of human life." But for atheists, though fully aware these natural disasters cause grief, there is comfort knowing that personal loss through events such as these are simply one of life's truths. In other words, shit happens. There is no rhyme or reason to it why bad things happen to people, it is simply a matter of circumstance. The same goes for periods of drought. The weather is going to do what it is going to do, and bowing down with your hands clasped together isn't going to change it. Thor is not charging up his thunderbolts, and Jesus isn't blowing clouds your way.
Secondly, praying for rain is absurd because the ability for it to be answered is 100%. It is a given that no matter where you are in the world, you will receive some sort of precipitation eventually. A prayer for rain is a sure bet. There is zero chance that it won't be answered. Even the driest place on earth, the Atacama Desert in Chile gets some rain, even if it is only an average of less than .004 inches per year. So if it is guaranteed, what is the point of asking for it in the first place? I suppose people pray for timeliness, for it to rain soon, and perhaps folks are more specific about the quantity desired. Well, that can be a bit disappointing I guess. I would refer you back to the previous point, which is that there isn't a god actually in control of it. If your prayer isn't answered post haste, well, that would be because you are talking to yourself while on bended knees, friend.
It is wasted breath to look to the heavens and ask for a divine drenching. But fret not, the drops of H2O will come in due time, with or without your pleas.