Here is a front view of our scene. We place a spray emitter over our ground.

Top view ... the square emitter is place right over the terrain:

Our settings for Spray:

Right click the emitter for properties and make this setting for a blur:

A Deflector is place over the terrain and the spray in bound to it.

For the rain, make a white material that is self illuminated to about 30. Apply to the emitter.

Finally, add some volume fog at the top: