Fallout 4

About this mod

Seasons Change is an ambitious project to add functional dynamic seasons to the game.

Permissions and credits
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Day 17 on the Advent Calendar of Merry Modding Days (https://concordstories.com)

Seasons Change is an ambitious project to add functional dynamic seasons to the game.

  • Trees change according to the seasons
  • Grass grows and dies according to the seasons
  • Weather features snow storms in winter time.
  • Snow covers everything outside in winter.

The Seasons

Autumn (September thru November)
- Trees have multicolored leaves
- Grass is mostly dead
- Dead leaf decals show

Winter (December thru February)
- Trees have no leaves
- Grass is dead and sparse
- Snow covers everything (optional)
- Weather features snow storms

Spring (March thru April)
- Trees have buds and some leaves.
- Grass has some green shoots.

Summer (May thru August)
- All trees have green leaves
- Lots of green grass


Install and activate like any other mod via your mod manager. Place as high in the load order as possible to prevent basic compatibility issues. Seasonal Snow.esl should go below Seasons.esm and is optional in case you want snow in winter or not.

Compatibility Notes

3rd Party Patches
These patches are maintained by 3rd parties and are listed for your convenience.

Advanced Needs 76
Advanced Needs 76 & True Storms
Advanced Needs 76 & Vivid Weathers
Advanced Needs 76 & True Storms & Vivid Weathers

Horizon Architect Weather Patch
Lightweight Lighting
True Storms
True Storms & Vivid Weathers
Vivid Weathers

This mod comes with pregenerated object LOD that dynamically changes with the season. It is incompatible with pregenerated LOD provided with any other mod. In order to be able to combine with other mods that require custom LOD, please generate your own LODs following my LOD Generation Guide (now with videos!).

Placed Tree References

This mod adds tens of thousands of separate tree crown references for each season over top of the existing leafless trees in order to work its magic. This is why it absolutely must be an ESM file plugin so that these references can be temporary and not cause you to exceed the reference handle cap. Any mod that adds or otherwise modifies placed tree references or derivatives thereof will potentially cause visual incompatibility and require advanced patching.

Tree Textures
Any tree mod that adds leaves to the Elm and/or Maple tree textures will cause visual incompatibility. One way to work around this is to install Make Like a Tree's leafless variants over top of it and allow its tree textures to override.

Seasonal grass is made possible by placing the deader grass high in the landscape texture record index and the successively greener grass in the higher indexes. Then it limits the number of grass types to show according to the MCM menu, which corresponds to the index. Grass mods will need to understand and respect this in order for them to be functional as a seasonal grass mod. Else, it merely will serve as reducing the amount of grass shown according to the season. There is no direct incompatibility, therefore, with grass mods, but they might not display as the grass author intended if not designed to work in this manner.

Seasonal weather is made possible by using globals to set the chance that a weather will spawn in the given region, which is modified via the seasons script. Currently it only modifies the chance of rainy weather versus snowy weather in winter. Other weather mods can safely override, they simply will not be seasonal. A specialized patch for any given weather mod would be required to make it properly seasonal. In the future this may potentially be performed automatically via an xEdit script.

NAC X has its own seasonal weathers, and it will override without conflict.

ENB Rain likes to override the snow textures with its own rain textures. I suggest disabling it.

This mod does not edit any vanilla precombined references, adding all new references for the tree crowns at the same placement as the vanilla tree references.


Snow will cover everything outside. There are some objects that do not like it and will not receive snow, most notably Moveable Static references (typically cars). This may also be items like wire mesh gates. If there is a transparent texture on such an item, anything you see beyond it will not have snow. If a static item has transparency and such an item is behind it, you will have snow on the transparency.

Do note that if you use Terrain Undersides, you will likely need to increase the height at certain locations where the snow will paint the underside, making it visible. This is accomplished in the MCM menu.

Z-fighting may occur against some items, especially items that are at the rotational medium point between receiving snow and not. This has been minimized, but you will still see it against some things.

On some items, the snow will hightlight the blocky low-poly parts of the mesh.

Upon cell change, you may notice a very brief flash when the snow is applied upon loading the cell.

It may be possible for the snow to not activate in rare cases. This can be fixed by using the MCM menu Fix Snow button. It may also be possible for the snow to look low resolution on objects after traveling for a very long time outside without entering an interior cell. This can also be fixed by using the MCM menu Fix Snow button.

xEdit Script

This is WIP and for advanced users only for integration with your mods. It will solve compatibility issues with various mods automatically by dynamically building the mod against your load order.

  • Set up the Seasons.bat to launch using your xEdit install location as the "Start In" directory.
  • Launch Seasons.bat.
  • Wait about 5 minutes for it to finish and close.
  • Regenerate LOD.

Mod Authors

If you would like to tie into this system, simply make a duplicate reference for each season that you would like your item enabled, and add an XESP - Enable Parent to the appropriate markers mentioned below. Do note that these markers were pulled from formid references in Fallout4.esm due to a game limitation for LOD Respects Enable State that only works for Fallout4.esm FormIDs. Therefore, it is important to set Seasons.esm as a master, as it may not be automatically added, and your items will be enabled depending on the random chessboards I pilfered to make this all work.

AutumnCommonwealthEnableMarker [REFR:0021B1F2]

WinterCommonwealthEnableMarker [REFR:000995D6]

SpringCommonwealthEnableMarker [REFR:00032B07]

SummerCommonwealthEnableMarker [REFR:000847C1]


Art Credit to the lovely artist at www.melaniteart.com for the Merry Modding Days

BadDogSkyrim and contributors for PyNifly
-Used to import and export nif files into Blender

Bethesda Game Studios for Fallout 4 and the Creation Kit
-Compiling scripts
-Creating SCOL nifs

ElminsterAU and the xEdit team for xEdit and the included BSArch Pro
-Placed tens of thousands of tree references in under a minute through the power of scripting
-Creating optimized archives with Shared Data and the ability to have compressed and uncompressed files in the Main archive

Neanka, reg2k, and shadowslasher410 for Mod Configuration Menu
-Used to power the MCM menu for the mod

Ousnius and Caliente for BodySlide and Outfit Studio and Material Editor
-Outfit Studio was used to create the tree crowns in order to preserve the vertex alpha for proper tree animations
-Material Editor for creating all the material files

Sheson for xLODGen and TexGen (included in the DynDOLOD 3 alpha file)
-Used to generate LOD

The Blender Foundation for Blender
-Used to create the LOD Models

The Gimp Team for Gimp
-Used to create textures

Veta Phoenix and greenFoxel
-The video trailer
-Organizing the Merry Modding Days

-bethini-doubleyou-etc in the Mod Author Hub