Why is my HDRP volumetric fog invisible?

Two switches required: HDRP Asset has Volumetrics enabled in the Lighting section, and a Volume in scene with Fog override has Volumetric Fog enabled. Both default off.

Volumetric Lighting too?

For light shafts through fog, enable Volumetric Shadow on the directional light. Without it, fog is uniform; with, you get god rays.

Volumetric fog cost scales with fog distance and slice count. Tune Volumetric Quality preset (Low / Medium / High) in HDRP Asset; Low uses fewer slices and is fine for most scenes.

Fix: Unity HDRP Volumetric Fog Not Rendering

Quick answer: HDRP Asset → Lighting → Volumetrics = on. Add Volume in scene → Fog override → Volumetric Fog = on. Set Mean Free Path / Fog Distance.

Game scene with HDRP. Add Fog override to a Volume. Nothing changes. The HDRP Asset itself disabled volumetrics at the project level.

The Symptom

Fog override visible in inspector, values change, scene renders identically with no fog volume.

The Fix

HDRP Asset (Project Settings → Quality → HDRP Asset):
  Lighting → Volumetrics:
    Enable:                       true
    Volumetric Quality:           Medium
  Lighting → Volumetric Clouds:
    (optional, separate)

Scene Volume (Global, priority 0):
  + Add Override → Fog
    Enable Fog:                   true
    Fog Attenuation Distance:     200
    Volumetric Fog:               true
    Volumetric Fog Distance:      64

Directional Light:
  Volumetric Shadow:              true   // for god rays

HDRP gates volumetric features at asset level for performance. Once enabled, scene Volumes provide local override.

Verifying

Look toward sky/distant geometry: fog falloff visible. Move directional light: shafts trace through fog. Disable HDRP Asset toggle: fog disappears.

“Asset toggle. Volume override. Fog renders.”

Related Issues

For URP decal on skinned, see URP decal. For shader keyword strip, see keyword strip.

Asset on. Volume on. Fog reads.