This mod was made by Kirel who has released his mods openly to the community. I had it saved but noticed it wasn't on Nexus mods but figured I would share it so people who may not be aware can use it. 200% credit to Kirel. I included 2 versions, the original mod and an updated one synced to more recent masters. Sometimes it gets stuck but a reload fixes it for me (mostly).

                 The Elder Scrolls III:
                      Morrowind
             Kirel's Interior Weather V1.0
                   featuring T-Rex!*
1. INSTALLING THE MOD
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To install the plugin, unzip the file into the Morrowind Data Files
directory. 
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2. WHAT IT DOES?
 
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Plays weather sound effects in interior cells, but not in places like
caves, ruins, etc and places you wouldn't expect to hear them - all
with little or no FPS hit.
The unique selling point of this mod is that it has interior weather
effects for cells added by any other plugins straight out of the box.
No need for patches or editing.
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3. PLAYING THE MOD
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From the Morrowind Launcher, select Data Files and check the box 
next to the k_weather.esp file.
The mod decides in real time what cells to play sound effects in or
not. While it's pretty good at getting it right it will very rarely
play sound effects where you wouldn't want them (ie: underground) or
not play them where you would want them. (Houses, for example) You
can edit the settings for a cell in game by using the "Weather Wand".
player->additem "k_weatherswitch" 1
Equipping this once will change cells that play sound effects to cells
that don't and vice versa. Alternatively, equiping this while sneaking
will turn on the "reset mode" - any cells you enter while in reset mode
will be reset to their default settings. To disable reset mode equip
the Weather Wand while sneaking again. A sound will play while you are
in reset mode so that you don't leave it on by mistake. You don't have
to leave it equipped or even carry it around all the time, you just need
it while performing one of the above actions. You can perform all the
actions via the console if you prefer not to have an item in your
inventory.
placeatpc "kug_marker" 1 0 0 0
(marks cell as "Underground" - no interior effects)
placeatpc "kag_marker" 1 0 0 0
(marks cell as "Above Ground" - interior effects)
set kug_erase to 1
(Toggles reset mode on - no sound will play is this is done via the console:
Be Ye Warned!)
set kug_erase to 0
(Turns reset mode off)
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4. Compatibility Issues
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This mod alters no cells so it should be fairly compatible with everything.
However, it does alter a few misc items and minor scripts. As far as I know
the only incompatibility here is the Kwama Egg Sack clashing with Herbalism
mods. If you let this load first the herbalism mods will work fine, you just
might have to use the weather wand in certain egg mines to disable the 
interior effects. Probably not though.
In theory you should be able to use this with other mods that add interior
weather effects if you wanted to, all it would do is play both effects. Could
be useful to fill gaps left by those mods in modded buildings. (As far as I
know this is the only plugin that has interior effects in mod-added cells.)
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5. NOTES ON THE MOD
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In Morrowind weather changes don't register with the game until the
transition from one type of weather to another is complete - if you
enter an interior during this transition then the interior effects 
for the previous weather type will play. Also, weather changes don't
register with the game in interior cells, so you may find you enter
an interior while it's raining, hear the rain effect but leave to find
it's now clear. As far as I know these are limitations of the game that
would be ineffcient if not impossible to work around. Another consequence
of this is that if you teleport from one interior to another the game
won't register the exterior weather for the new cell, and you'll still
hear the effects for the previous cell. Again, limitations of the game.
Something that opinion may be divided on is interior weather effects in
Vivec - personally I like them but I can see that others may think that
the Canton walls are too thick for sound to penetrate. If you decide you
don't like the effects you can use the weather wand to turn them off.
ALWAYS backup your savegame before using a new plugin. You use 
plugins at your own risk.
Cleaned with Tesame.
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6. Thanks & Credits:
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- Sounds taken from Atmospheric Sound Effects by Duncan - slightly edited.
- Thanks to the author of the readme I copied over! ;)
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7. Usage:
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Scripts in this mod are mine. If you want to use them, you must ask me
first. I don't think there's a way of saying that without sounding like
a jerk, but still. ;)
To be honest, I can't see a valid reason why this should be used in
another mod. As far as any improvements etc, I'd like you to email me
rather than releasing your own version, which seems fair don't you
think? - [email protected]
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*Not really.