<P>PrecipitationSounds can be used to add ambient sounds that turn off or change when weather is disabled. The sound of the rain falling on the water here gets replaced with much a lower-key water lapping sound when weather is disabled.  You can also use PrecipitationSounds to add ambient sounds that only play when weather is disabled.
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<P>You sould also use PrecipitationZones for your water zones, to keep the rain from stopping as soon as you jump in.  In addition to setting bWaterZone to true, you'll want to copy over the entry/exit actors/sounds, ViewFog, and AmbientSound from the regular WaterZone.  You can even make underwater PrecipitationShelter zones, if you can contrive a use for such a thing.