Ue Udw Setup And State

UDW setup and weather state

The foundation of Ultra Dynamic Weather: getting the actor in place, the weather state model, presets, runtime transitions, the manual state for sequencer/per-value control, sampling weather from gameplay code, and event dispatchers.

When to use this skill

• Adding UDW to a level for the first time.
• Choosing or applying a weather preset (Rain, Blizzard, Thunderstorm, etc.).
• Triggering a weather change from gameplay code.
• Overriding individual weather values without writing a new preset.
• Reading current weather from a blueprint (state values or display name).
• Wiring game events to weather transitions (sunrise of a storm, end of snowfall).
• Tracking how exposed an individual actor (player pawn) is to weather.

Adding UDW to a level

UDW requires UDS — make sure there's an Ultra Dynamic Sky actor in the level first (see ue-uds-setup-and-modes).

Drag an Ultra Dynamic Weather actor from the Blueprints folder into the scene. It detects UDS automatically and hooks everything up.

By default, UDW starts with a manual weather state matching the Cloud Coverage and Fog already set on UDS. The Weather variable in Basic Controls lets you apply different weather presets immediately.

Basic Controls

Advanced dropdown holds additional knobs (Control Point Location Source — see ue-udw-spatial-weather; configuration override — see ue-uds-modifiers-configs-state).

Weather state

The set of values that defines "what weather is" right now.

Plus material state — drives material effect functions:

The visible material state at runtime isn't always directly the weather state values — see ue-udw-material-and-screen-effects for the Simulate Changing Material State Over Time option.

What determines weather state

The active state can come from any combination of these sources (specificity layers from global → local):

Weather Settings Presets

Preconfigured weather states as data assets. Used by Weather, Change Weather, Random Weather Variation, Weather Override Volumes, and Radial Storms.

Blueprints/Weather_Effects/Weather_Presets/
   ├── Rain
   ├── Partly_Cloudy
   ├── Blizzard
   ├── Thunderstorm
   └── ...

Creating custom presets

Easiest: duplicate one of the included assets in Blueprints/Weather_Effects/Weather_Presets/ and edit its settings. Your new asset works everywhere the included ones do.

Custom Weather Behavior (per-preset Blueprint logic)

The UDS_Weather_Settings data asset class has a Custom Weather Behavior function meant for override. To add custom logic to a preset:

1. Create a child of UDS_Weather_Settings
2. Override Custom Weather Behavior
   (parent applies the Sky Modifier on the preset — call Super if using one)
3. Make data assets using the child class

The function has an Alpha input (0–1): how much this preset is currently affecting local weather state. Called at runtime as weather state changes in any way involving this preset.

Change Weather

To trigger a weather change at runtime (instantly or over a duration):

UDW.ChangeWeather(targetPreset, transitionLengthSeconds)

The new global state stays applied indefinitely, until another change is called for.

Manual Weather State

For individual weather values without a preset. Category: Manual Weather State.

1. Clear the Weather setting in Basic Controls (no preset selected)
2. Edit values in the Manual Weather State category — they become active

Per-value overrides

Override one value while keeping the rest from a preset. Example: Thunderstorm preset is active, but set Manual Rain Override = true and pick a custom Manual Rain value — rain comes from your manual value, everything else from Thunderstorm.

Each weather state value has an override toggle and a manual value pair in this category.

Sampling weather state (runtime)

Get Display Name for Current Weather is what to call when you want to surface a weather label in UI without parsing individual values. For temperature, see ue-udw-random-seasons-temperature.

Weather event dispatchers

Bind events from your blueprints. Pattern:

UDW = GetUltraDynamicWeather()
UDW.OnStartedRaining.AddDynamic(this, &MyActor::OnRainStart)
// Or in Blueprint: Bind to Started Raining → Custom Event

The threshold for the started/finished dispatchers is in the Event Dispatchers category on UDW.

Actor Weather Status component

Per-actor weather tracking. Intended for important actors (e.g. the player pawn) that need to constantly monitor their own status.

At runtime, the component periodically traces to test exposure and tracks how the actor's temperature is affected. All values are in the component's Status category.

Features:

One-off exposure query without a component

UDW.TestActorForWeatherExposure(actor) → rain, wind, snow, dust (each 0-1)
// Floats combine weather intensity with actor exposure.
// 1.0 = fully exposed to that effect at max intensity.

Sequencer

To animate the weather state in Sequencer, use Manual Weather State and keyframe its variables.

For material effects (Material Wetness/Snow Coverage/Dust Coverage), to make keyframes look identical at runtime to in-sequence: in the Material Effects category, disable Simulate Changing Material State Over Time. Otherwise runtime gradually transitions between values instead of matching keyframes precisely.

Multiplayer replication

UDW replicates weather state for multiplayer:

Result: updates only need to go over the wire when a state-source change starts. Between updates, clients track state the same way the server does.

Gotchas

• Cloud Coverage / Fog on UDS ignored — UDW is in the scene; it owns those values. Set on UDW's weather state instead.
• Change Weather doesn't appear to transition — transitionLengthSeconds was 0 (instant change). Pass a duration for a smooth transition.
• Setting Weather to a preset has no effect at runtime — preset assignment is editor-time. Use ChangeWeather(preset, duration) from blueprint to switch at runtime.
• Material wetness/snow doesn't match keyframes in Sequencer — Simulate Changing Material State Over Time is on. Disable it for direct keyframe playback.
• Manual Rain value ignored — Manual Rain Override is off. Override toggles must be enabled for per-value manual values to apply.
• Weather display name shows "Manual Weather" — no preset is selected; UDW falls back to Manual Weather State. Set the Weather variable or call ChangeWeather(preset, ...).
• Per-actor wetness in materials not working — the material's Use Local Parameters pin isn't set, or the dynamic material instance wasn't added to the Actor Weather Status component's Material Effects array.
• Started Raining / Started Snowing fires at the wrong threshold — adjust thresholds in the Event Dispatchers category on UDW.
• Random Weather Variation overriding ChangeWeather — call ChangeToRandomWeatherVariation() to return control, or disable Random Weather Variation in its category.

References & source material

Docs (Ultra Dynamic Weather 9.5):

• Adding Ultra Dynamic Weather to Your Level
• Basic Controls
• What is Weather State?
• What Determines the Weather State?
• Weather Settings Presets
• Change Weather
• Manual Weather State
• Sampling the Weather State from UDW
• Weather Event Dispatchers
• Actor Weather Status
• Custom Weather Behavior
• Technical Notes — Replication (UDW)

Plugin asset paths:

• Blueprints/ — Ultra Dynamic Weather actor (drag from here)
• Blueprints/Weather_Effects/Weather_Presets/ — included preset data assets (UDS_Weather_Settings)
• Blueprints/Weather_Effects/ — Actor Weather Status component

Related skills: ue-uds-setup-and-modes (UDS must exist first), ue-udw-random-seasons-temperature, ue-udw-spatial-weather, ue-udw-particles-lightning-wind-sounds, ue-udw-material-and-screen-effects, ue-uds-modifiers-configs-state (Apply Weather Configuration, save/load state).