I finally got it to rain in the monsoon mission in fsx.
I had tried everything. Nothing seemed to work.
Then, I tried the following.
On the startup page, I checked "enable changes".
while in the mission, press the alt key. In the drop
down menu up top of page select weather.
look around for advanced or customize.
click on it. There you will find, how to make
it rain, complete with rain effects. Snow if you please.
Then when you fly the monsoon mission, You now
will have rain complete with rain effects.
It worked for me. I hope it works for others.
Problem is you dont get rewards. And A big hello to the forums, (but i see 5 years later.) 😀 Keep in touch here!
SP 1 fixes it