The main still hardcoded limitation is that the Lightning % Chance cannot be altered, and must be set in the area properties. It might be worth, if adding custom weather, to remove the ModelLightning for snow so you can have snow without huge thunder and lightning if you want to retain it for rain.
|Column Names||Example||Valid Values||Description and Notes|
A human readable label unused by the game
|MDL file name|
Model to load that follows the player around
|Animation||rain||Animation name in MDL||Animation to play in the vfx for the weather|
|ModelLightning||fx_lightning01||MDL file name||The model used when the Lightning % chance was|
|FadeTime||6000||Integer||The amount of time in milliseconds it takes to fade the weather out (where the intensity of the rain/snow ramps up to 100, or down to 0). 6000 would be 6 seconds.|