These are the settings I use:
Fog=0
FogRand=1
Clouds=1
CloudsRand=1
Precip=0
PrecipRand=1
WindHeading=0
WindSpeed=4.000000
WindRand=1
WeatherRndInterval=2
The original RealWeatherFix settings are these:
Fog=1
FogRand=0
Clouds=1
CloudsRand=0
Precip=0
PrecipRand=0
WindHeading=0
WindSpeed=4.000000
WindRand=0
WeatherRndInterval=5
Just make sure these settings are the same in all three Campaign files.