Disclaimer:
Heavy Fog weather condition will may have affect on psychological condition. I will take no responsibility for absence of a mental disorder after using this mod for the long period of time or the lack of your mental health afterwards.

The possible psychological disorders that you will get or possible won't get after long usage of this mod:
Anxiety Disorders; Bipolar disorder; Major depressive disorders; Disruptive mood dysregulation disorder; Premenstrual dysphoric disorder;
Sleep - Wake Disorders; Acute stress disorder; Adjustment disorders
Viewer discretion is advised.

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UPDATE 1.02 RELEASE

FEATURES :

- Remove Override and Priority flags from some regions. Should be more proper weather type transitions (tell me if you see something behaving) -
- To all additional regions (Like Diamond city) added full moon phases like in Default Cycles. By FO4 default it was simple moon for those -
(only makes sense in Enhanced Weather. Cause in all FOG variants you don't see moon much - cause FOG)
- Tweaked Sun rotation cycle in all regions to be as Default Cycles. By FO4 default it was slightly different time for dawn, dusk, etc. -
- Added additional  Enhanced Weather.ESP plugin which is pretty much as default but more proper and with fixes, full moons, sun timings, etc. - 
(Enhanced Weather - my personal weather tweaks which I use in main walkthrough. For exac percentage - see the screenshot on page # 2)
- Slightly decreased frequency shift for weather type rotation change (all plugins) -
- Added additional versions by user requests -
(not fully tested; not recommended to use to everyone else)

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UPDATE 1.01 RELEASE

From now on mod name will be "Fog of War". Credits for the name goes to @BoogieLove and @Nedellis for idea to change it in the first place
If you upgrading from previous "Silent Hills" version: delete old .ESP and add this one - Fog of War.esp

FEATURES :

- Added DUST STORMS to Polluted variation -
- Fixes on foggy weather cycles not being working in all areas (not all of them: till GECK or new FO4Edit ver.) -
- Tweaked sun cycle in special areas (such as Diamond city) to be as in Default outdoors weather cycle -
- Other minor tweaks -

More about "weather cycles not being working in all areas" :

Till GECK release or a new version of FO4Edit which allows me to filter data w/o bugs I can't find all duplicate conditions in all regions and events.

This is a minor issue really, cause the solution itself are the simple one -
IF you encountering some unexpected weather type (for instance: clear sunny day in FOG version) you should sit and wait (anywhere outdoor) for several hour for your installed (FOG, MIST, etc.) type of weather; Then you should fast-travel to somewhere further from your current location
This issue will be mostly occur at Diamond City travel for the first time after mod install and on Diamond City exit

You should be doing this proper just one time - After all of that your save data will be refreshed with new weather cycle and all will be good
shiny and chrome.

More about SAND STORMS :

Sand (Dust) Storm are not present in default weather cycle. And it is not fully finished effect by BETH itself: at night sand storm will be white;
at any day time it will be orange (see screenshot, page # 2). Thus it will be out of place in general game tone which is vivid and bright.
There is no desert in Boston for Sand Storm to naturally occur. There is not that much sand either. Logical? :D 
Thus I will add this only in Polluted version as "miscellaneous" variation of original Polluted.
Cause I don't have patience for manual color edit of each layer...maybe some other time....or with more comforting tools. 

More about POLLUTED again :

Polluted weather type is not present in default weather cycle either. It is also a "special" condition type.
There is no existent Rain type (or I didn't find any) which will have proper transition between "Polluted" and "Rain".
For "Clear day" to "Rain" we have "Clear Rain" type. For "Foggy day" we have "Misty Rain"
Both of them will be very rough and very out of place on "Polluted" transition.
Thus I removed rain from "Polluted" version and increased Radiation Storms as counterbalance of rain absence.

More about 1.01 variations :

- FOG - 85% of the time it's heavy Fog + 10% Rain with Fog + 5% RAD Storm -

- MIST - 85% of the time it's Misty Fog + 10% Rain with Fog + 5% RAD Storm -

- MOSTLY FOG - 60% of the time it's heavy Fog + 25% Misty + 10% Rain with Fog + 5% RAD Storm -

- MOSTLY MIST - 60% of the time it's Misty + 25% Fog + 10% Rain with Fog + 5% RAD Storm -

- POLLUTED - 85% of the time it's Polluted Fog + 15% RAD Storm -

- POLLUTED with SAND STORM - 85% of the time it's Polluted Fog + 10% Sand Storm + 5% RAD Storm -

WEATHER ID's (Console Commands) :

CommonwealthClear; fw 0002b52a
CommonwealthFoggy; fw 001c3473
CommonwealthMisty; fw 001cc186

CommonwealthMistyRainy; fw 001cd096
CommonwealthPolluted; fw 001eb2ff
CommonwealthDusty; fw 001f61a1

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Hey

Long story short. This is my simple weather conditions mod

It changes all standard weather conditions to Gorgeous Foggy with variations:
Foggy; Misty; Mostly Foggy; Mostly Misty...Polluted-Foggy-kinda-Misty-Mostly-Sort-off-ish;
Please note: It will not change weather with special story-wise conditions and such OR any lighting values for sky/ night/ day and such
IT ONLY changes climate types percentage cycle

WHY creating this mod?! Cause "YES, WE CAN!" Also, cause foggy weather looks awesome in FO4
And for the most part I created it cause I wanna to check my thoughts on increasing in-game FPS. Let me explain:
You probably know that FO4 engine is old and it struggles on rendering shadows and objects which is a f-lot in this game
So, I was thinking WHAT if we change all weather conditions to "HeavyFog" and change lod/ shadow draw distance settings to almost minimum?
We will be maintaining high amount of FPS and without noticeable pop-ups in shadows and objects draw, right?
...because "HeavyFog" will block our view range anyways!
Thus I created this mod. In-game FOG looks awesome, horrific-mystic feel all the way and with high FPS amount with lower settings
at almost no visible (cause=FOG) image quality degradation
Awesome

Tho I'm not considering to walk-through entire game with this mod
I almost certain that this foggy weather will eventually will be getting on my nerves after 50 hours or so of gameplay
BUT you can always try it. It's FREE! =D

Now. For compatibility with other mods:

Should be compatible with ANY RESHADE/ ENB mods
This mod should be 100% compatible with Fr4nsson's Light Tweaks
This mod should be 100% compatible with Darker Nights by @unforbidable
This mod should be 100% compatible with Rad Storm Survivor by @Forzane
This mod should be 100% compatible with Heavy Rain by @Meltus
Should be compatible with ANY pure "Lightning" mod which doesn't alters weather cycles
My mod will not compatible with ANY mod which alters outdoors "Default Climate" percentage cycles
But why bother with other weather mods? I mean, IF you seek "FOG-all-the-time" - this mod has it. Just a FOG
Other weather mods just brings weather types altogether...Multiple-various weather - like default does it and like it should be
Also, post you favorite and popular mod name in comment section and i will eventually check it

I strongly NOT RECOMEND to use any "fog-remover" in outdoors areas
I mean, if you removing outdoors fog in the first place what use you'll get from my mod, right?
Tho this mod works absolutely fine with indoors "fog-remover" - I'm using FogOut mod for this purpose myself...

Now. For details on mod variations:

- FOGGY - 80% of the time it's heavy Fog + 15% Rain with Fog + 5% RAD Storm -

- MISTY - 80% of the time it's Misty Fog + 15% Rain with Fog + 5% RAD Storm -

- MOSTLY FOGGY - 70% of the time it's heavy Fog + 15% Misty + 10% Rain with Fog + 5% RAD Storm -

- MOSTLY MISTY - 50% of the time it's Misty + 35% Fog + 10% Rain with Fog + 5% RAD Storm -

- POLLUTED - 90% of the time it's Polluted Fog + 10% RAD Storm -

More about POLLUTED :

It's a "special condition" weather type. Not used in regular weather cycles. Foggy-Misty-Polluted with washed out colors
Very post apocalyptic and suicidal. See the screen-shots. OR even better - TRY IT!
Tho I'm not taking any responsibility for your suicidal thoughts after using this version long enough!
Be advised, people!

NOTE :

FO4 Default in-game percentage for RAD storm - 4%; for rain conditions - 11%

INSTALL :

- Copy .ESP file in to "Data" folder ("Fallout4.exe" location) -
- Open "plugins.txt" and after "Fallout4.esm" add my plugin name -
- Save the file. Put "read only" attributes on "plugins.txt" -

DONE

PS. New weather condition will hits after few hours of sleep.
Or just fast travel to somewhat further. After this it will be always as in my mod...till you delete it

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My other mods:

Simply Better Laser Sound FX

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Simply Awesome PIP-Boy