WorldWeather

This is the full list of what the API gives you, one section for each part. Text in brackets at the end of a note is extra detail for experienced modders, and you can skip it on a first read.

WorldWeather reads the weather and changes it. The game has a list of weather profiles, called the global weather. Each profile is a named weather with an index counted from 0. NameOf and IndexOf turn one into the other.

WorldWeather read and set the global weather

Use these to read the weather now, Set to change it, and WeatherChanged to hear when it changes.

public static partial class WorldWeather
{
    public static event Action<WeatherChangedArgs> WeatherChanged;

    public static bool IsAvailable { get; }

    public static int Count { get; }
    public static int CurrentIndex { get; }
    public static string CurrentName { get; }
    public static float Temperature { get; }
    public static float RainIntensity { get; }
    public static bool IsRaining { get; }
    public static float SnowIntensity { get; }
    public static bool IsSnowing { get; }
    public static float WindSpeed { get; }
    public static bool IsThunderActive { get; }

    public static string NameOf(int index);
    public static int IndexOf(string name);
    public static bool Set(int index, float transitionSeconds = 0f);
    public static bool SetThunder(bool active);
}

Property	Type	What it means
`IsAvailable`	`bool`	`false` when the weather change event could not be set up.
`Count`	`int`	How many global weather profiles there are.
`CurrentIndex`	`int`	The index of the current weather. `-1` when there is no weather system or the default is active.
`CurrentName`	`string`	The name of the current weather. `null` when not ready.
`Temperature`	`float`	The temperature the game uses. `0` when not ready.
`RainIntensity`	`float`	How hard it rains right now: the average of light, medium and heavy rain.
`IsRaining`	`bool`	`true` when it is raining.
`SnowIntensity`	`float`	How hard it snows right now.
`IsSnowing`	`bool`	`true` when it is snowing.
`WindSpeed`	`float`	How strong the wind is right now.
`IsThunderActive`	`bool`	`true` when thunder is on.

Method	Returns	What it does
`NameOf(index)`	`string`	The name of a weather. `null` when the index is out of range.
`IndexOf(name)`	`int`	The index of a weather by name. `-1` when not found.
`Set(index, transitionSeconds)`	`bool`	Changes the global weather. Returns `true` when it worked.
`SetThunder(active)`	`bool`	Turns thunder on or off. Returns `true` also when it already was that way.

Event	Gives you	When it fires
`WeatherChanged`	`WeatherChangedArgs`	The weather the game is heading for has changed. `args.Index` is its index, `-1` when it is the default.

WeatherChangedArgs what WeatherChanged tells you

WeatherChanged gives you this when the weather changes. Index is the index of the weather it changed to.

public sealed class WeatherChangedArgs
{
    public int Index { get; }
}

Property	Type	What it means
`Index`	`int`	The index of the weather the game is heading for. `-1` for the default.

Things to know

The weather values give plain defaults when the game has no weather system. That is on the main menu or while a save loads. Count is 0, CurrentIndex is -1, CurrentName is null, and the numbers are 0.
Set(index, transitionSeconds) changes the global weather, and the sky blends over transitionSeconds. The game’s own timer for the next random change is not reset, so the weather can change again later. (It calls the game’s WeatherManager.SetWeather(index, true, transitionSeconds).)
WeatherChanged fires after the game has changed the weather it is heading for. That includes changes made by the game’s random timer, by your Set, by a save loading, and by any other game call. It does not fire for each frame of the blend. (It is raised after WeatherManager.ChangeWeather.)
SetThunder turns thunder on or off. No event is raised. (It calls WeatherManager.StartThunder and StopThunder.)
Forced thunder can stay in a save. A save made while thunder is forced can keep it. It lasts until the next Set of the weather, which sets thunder again from the profile’s heavy rain and the game’s thunder chance. (The game’s field carries [fsProperty].)
IsAvailable tells you whether WeatherChanged works. It is false when the framework could not set up the event, or when its feature group was turned off. Reads are not affected.

Limits

Set throws an ArgumentException for a bad number. That is a negative index, or a transition that is negative, NaN or infinite. It does this even when no weather system is ready. Once a weather system is ready, it also throws for an index outside 0..Count-1.
Set returns false for other problems. That is when no weather system is ready, when the profile is missing, and while a save is loading or being written.
If the game stumbles during Set, you may still get true. When the game call throws but the weather you asked for is now active, Set raises WeatherChanged itself and returns true. Otherwise it returns false and nothing is raised. The failure is logged. (The game retargets the weather before the exception can happen, and the framework’s change to ChangeWeather does not run after a throw.)
Thunder alone does not always show lightning. Lightning flashes only while the sky is not overridden and no weather change is blending. SetThunder(true) alone shows no lightning in those states.
Fog is not available. The game has no fog setting to read. (AzureFogScattering is a visual component only.)

Weather zones

A weather zone is an area in a scene with its own local weather. While the player is in or near a zone, the game blends the zone’s weather over the global weather. The distance over which the zone fades in is its blend distance. A scene can have no zones at all. Then Zones() is an empty list.

WorldWeather weather zones

Use SetZone to give one weather zone its own weather, and ClearZones to remove your mod’s zones.

public static partial class WorldWeather
{
    public const float MaxZoneBlendDistance = 10000f;

    public static List<WeatherZoneInfo> Zones();
    public static bool SetZone(string modId, string zoneId, int weatherIndex, float blendDistance);
    public static bool ClearZones(string modId);
}

Property	Type	What it means
`MaxZoneBlendDistance`	`float`	The largest blend distance you can set, in metres.

Method	Returns	What it does
`Zones()`	`List<WeatherZoneInfo>`	The weather zones the game has in this scene.
`SetZone(modId, zoneId, weatherIndex, blendDistance)`	`bool`	Makes a zone use one of the global weathers.
`ClearZones(modId)`	`bool`	Takes back every zone change your mod made. Returns `true` when it had made one.

WeatherZoneInfo a snapshot of one weather zone

Zones() gives you one of these for each weather zone. Overridden says whether a mod has changed the zone with SetZone. (It reads the game’s AzureWeatherZone.)

public sealed class WeatherZoneInfo
{
    public string Id { get; }
    public bool Active { get; }
    public float BlendDistance { get; }
    public string ProfileName { get; }
    public int WeatherIndex { get; }
    public bool Overridden { get; }
}

Property	Type	What it means
`Id`	`string`	The zone’s id in the scene. Use it with `SetZone`.
`Active`	`bool`	`true` when the zone is switched on and can take effect.
`BlendDistance`	`float`	The distance in metres over which the zone fades in.
`ProfileName`	`string`	The name of the weather the zone applies now. `null` when none.
`WeatherIndex`	`int`	The index of the global weather with that same profile. `-1` when it is not one.
`Overridden`	`bool`	`true` while a mod’s `SetZone` is in force.

Things to know

Zones() lists the zones the game has registered, in the game’s order. The game’s own sky-override zone is left out, because the game rewrites it whenever the player enters or leaves one of the places that use it. Zones register about 0.1 seconds after a scene starts, so wait a moment after the scene load before you list them. (The zones are AzureWeatherZone components. Active is true when the zone’s collider is enabled and its object is active. The left-out zone is the one used by scenes with an overridden sky and by the shop controller.)
SetZone makes a zone use one of the global weathers. weatherIndex is the same index as Set and NameOf. blendDistance is from 0 to MaxZoneBlendDistance metres. It does not change the global weather: Set and WeatherChanged are not affected, and only the player’s sky and effects near the zone use the change.
The newest SetZone call wins. Each mod keeps one change for each zone, and for a zone the newest call among all mods applies. When a second mod sets a zone that another mod already set, one warning names both mods.
ClearZones(modId) takes back that mod’s changes. The change set before it applies again. When none is left, the zone goes back to the weather and blend distance it had before the first change.
SetZone and ClearZones work at any time. They work inside Events.SceneLoaded and while a save loads or is being written, because the changes are not saved and the game does not save a zone. (AzureWeatherZone is not a savable component.)
A zone change never edits the game’s weather files. The framework only points the zone at an existing weather. The global weather and other zones are not affected. (A zone’s profile and blend distance are plain data on the component. The framework swaps the zone’s reference to an existing profile and never changes a profile asset.)

Limits

SetZone returns false when the input is not allowed. That is an unknown or empty zone id, a weather index that does not exist, a blend distance out of range or not a number, and no weather system. An invalid mod id throws an ArgumentException.
Zone changes last for the session only. They are not saved. Every single-scene load puts the zones back and clears all changes, so set them again from your Events.SceneLoaded handler. An additive load (a neighbouring scene loaded alongside) does not clear them.