Rain spell

Start by closing your eyes, visualize the rain. How heavy you want it to be, how long, how it feels on your skin. 

Open you eyes. If you have a wand, point it to the sky and say,

"Water nymphs on the sky,

Let the rain fall from up high.

Let the flowers bloom,

To make up for the rain's gloom."

Pause and visualize the rain again, they say,

"three times three, so mote it be"

I tested this a few times, and it will more than likely take a while, but it should work as long as it's cloudy