I was tired of bad weather making me see jack when exploring houses or even in the wilderness, at noon. I don't know Arizona that much, but it does not seem to me that noon should as dark as midnight when raining, and even darker when storming. So I changed that.
I lent on other mods to make mine, as I was not satisfied with them. The result is pretty satisfying for me, so I decided to upload my mod to share with others.

Simple description :

It's simple really. I downloaded GNS Weather Mod, and also Clear Skies from BluemaxDR, which I liked. But the first wasn't too efficient, and the second was to unforgiving and not making bad weather less dark. So I mixed both of them and played with the values, which I tested for many hours, and the balance I obtained is what I like the most.
You will see dark storms where you won't see jack, but overall storms and rainy days will be lighter, both in terms of length and in terms of average ambient lighting.

What does the mod actually change ?

Technical stuff :

I wanted to have soe bad weather because immersion is important to me. But that dark side (teehee) of this is you can't see anything while exploring, even outside. So I played with a value called "Cloud Thickness" which commands the game to cloak the surrounding sky into clouds, which in return, lower the ambient light level. I realized that this value was the one to play on if I wanted my bad weather to allow me at least some sight in case of danger, without having torches, fire shaft mods, or helmet lamps. At the same time, allow some bad weather to come sometimes was the element of surprise I needed to make me go "oh shyte I need to be extra cautious" but at least I can still see somewhat, somehow.
I also played with another value, the "fog", which means real fog you wan see when exploring, like smoky particles. And this, my friends, is something that's present everytime, I mean for every bad weather types, and impairs the view, so I halved the value of the thickness of the fog particles for a direct result on ability to see danger from afar, peripheral vision wise. It means if you're like me, you play relying on your instinct and peripheral vision instead of relying directly on your frontal vision, and making fog thinner allows your vision to detect more movement, like T-Rexes in Jurassic Park if you will.

Technical values below :

Values below will be displayed in that order for each weather type :
Weather type : Chance ; Cloud Thickness ; Precipitation Level ; Fog particles ;

Snow biome : (overall less snow for more sun, and if snowy weather, more chance of it to be clearer and less foggy)

Normal weather : 70% from 44% ; max 0.8 from 2.0 ;
Foggy weather : 10% from 8% ;  25 - 45 from 35 - 60 ; 5 - 15 from 7 - 18 ;
Snowy weather : 15% from 40% ; 40 - 60 from 55 - 75 ; max 50 from 60 ; 0.5 - 2.5 from 1.0 - 5.0 ;
Storm : 5% from 8% ; min 60 from 90 (max is still 100) ; 50 - 80 from 70 - 100 ; 2.5 - 7.5 from 5 - 15 ;

Pine Forest : (overall weather is sunny and less cloudy, and if raining the light level will be higher in average)

Normal weather : 90% from 83% ; 0% cloud thickness 75% chance up from 35% / cloud thickness 10 - 50 from 10 - 70 put to 25% chance down from 65% ; max 0.5 from 2.0 ;
Foggy weather : 5% from 7% ; cloud 40 - 60 from 70 - 90 ; 5 - 15 from 7 - 18 ;
Rainy weather : 4% from 7% ; 40 - 60 from 55 - 75 ; max 50 from 60 ; 0.5 - 1.5 from 1.0 - 3.0 ;
Storm : 1% from 3% ; min 60 from 90 (max is still 100) ; min 50 from 90 (max still 100) ; 1 - 4 from 2 - 8 ;

Desert : (overall less clouds and rain and almost no storm for a bigger surprise when heavy rain)

Normal weather : chance 97% from 87% ; 0% cloud thickness 80% chance up from 33% / cloud thickness 10 - 20 from 10 - 50 put to 20% chance down from 66% ;
Rainy weather : 8% from 15% ; 30 - 60 from 75 - 90 ; max 40 from 80 ; 0.5 - 2.5 from 1.0 - 5.0 ;
Storm : 2% from 5% ; min 60 from 90 (max is still 100) ; min 50 from 90 (max still 100) ; 1.5 - 7.5 from 3 - 15 ;

Wasteland : (overall less clouds and rain and more light if raining)

Normal weather : chance 90% from 80% ; 0% cloud thickness 80% chance up from 30% / cloud thickness 10 - 40 from 10 - 70 put to 20% chance down from 70% ;
Rainy weather : 8% from 15% ; 30 - 60 from 75 - 90 ; max 40 from 80 ; 1.0 - 2.5 from 2.0 - 5.0 ;
Storm : 2% from 5% ; min 60 from 90 (max is still 100) ; min 50 from 90 (max still 100) ; 1.5 - 7.5 from 3 - 15 ;

Burnt Forest : (overall less rain and more light if raining)

Normal weather : chance 88% from 75% ; 20 - 40 from 40 - 70 ; max 2 from 5 ;
Rainy weather : 9% from 15% ; 20 - 50 from 70 - 85 ; min 50 from 80 ; 1.0 - 2.5 from 2.0 - 5.0 ;
Storm : 3% from 10% ; min 50 from 90 (max is still 100) ; min 30 from 90 (max still 100) ; 1.0 - 7.5 from 2 - 15 ;

Credits go to GNS and his mod, and BluemaxDR for his too. Max credit to TFP for feeding me up with their buggy engine, no worries guys, but work more on your light engine and weather engine too because it's annoying.

My other mods :

See my User Files.