I wasn't just guessing. The readme has the correct answer to his question.
And to save a little time for anyone who is interested, here is the pertinent section:
[density] exec "\KEGnoecain_snow\script\snow.sqs"
Creates a snowfall. Density is an integer that defines the density
of the snowfall (higher = more snow). If density is not specified a
default of 5 is used. Note that the maximum working density value
is relative to the FPS.
But it is worth checking anyway: The result? Setting the weather bar all the way to the left only creates an overcast sky with lightning. No snow.
***EDIT****
Hey Peter, don't delete your posts. It makes me look like I'm talking to myself ;D ;D