This mod provides volume control over the thunder noise created by lightning bolts. No more setting the Weather slider to "OFF". Enjoy the rain alongside the thunder.
Technical
The mod accomplishes this by hooking onto the PlaySound event and filtering for ambient.weather.thunder. The volume is then reduced considerably (from 10000.0f to 5.0f) before it plays. It does this for any volume above 5 to try and catch some modded thunderbolts too (such as Weather2, which uses 64.0f). The default volume of 5.0f was chosen according to a comment on the relevant bug MC-46634.
Global thunder
Enabled by default is a simple algorithm that plays the sound near the player, in the direction of the thunderbolt. It also affects the thunder's volume. See the configuration file for details.
FAQ
Will you port this to [version]?
Only if enough people want it. Otherwise, probably not. I created this mod for a small modpack that I play on with a friend, and I thought I'd share it since I couldn't find a mod that does this.
Isn't this already fixed by BugTorch?
Yes, sort of. BugTorch uses a mixin to patch Minecraft's EntityLightningBolt class. This means it is fixed for anything that uses the vanilla lightning bolt. Despite this, setting the volume too low means you won't be able to hear it unless it's quite close to you, and setting it too high means it will still explode your ears even if you have the Weather slider set really low.
This mod uses a different approach by intercepting the actual thunder sound and reducing its volume before it is played. This allows coverage for mods using the thunder sound. Additionally, this mod tries to place the sound near you so that you can still hear thunder bolts that are far away, while also being able to control the volume.