Acid rain in certain areas where the sky is heavily polluted from smog if after a nuclear war 200 years later there ends up being some industrial factories using oil to burn or coal to burn can work.

In Fallout 3's expansion pack The Pitt if you remember it is a pretty industrialized area. Acid rains can happen in The Pitt if Bethesda Game Studios developed a weather system like that for Fallout 3.

The radiation from nuclear bombs exploding should also cause acid rain. In certain areas only.

Good news, the scene with the airship confirmed both.

The scene with the deathclaw gave me the impression that maybe there will be an area full of deathclaws and sandstorms. Sounds cool in theory but I can see people absolutely despising this area if that's the case.

No acid rain.

None.

Not even once.

Why?

'Acid' rain.

It would be a catastrophic event for the region where so much vegetation and wild-life would die off that Bethesda would need to have every single NPC react to it to various extents.

Seriously. We're talking about 'acid rain'. It'd [censored] up next to all vegetation and any herbivore which had the brains to seek shelter would get sick trying to eat the grass the days following.

And that's not even going into how it'd [censored] up buildings and shelters which civilized NPC's reside in.

I do not want to see acid rain and have absolutely zero reactivity from NPC's and the wild-life.

Acid rain can't happen just for the player. It has to happen for 'everyone'. And Bethesda already spreads themselves too thin as it is with their dialogue and reactivity. Acid rain, in any capacity, would either spread that even thinner or be completely detached from anything else in the game but the player. And with the latter; What's the point? I don't care about having yet another survival element. If acid rain happened I would love to hear what other NPC's have to say about it. How freaked out they are about it. How disasterous it was to any farmer or rancher. That is interesting to me. The people. Not some stupid acid rain just shoehorned in because "it's cool".

Anyway, it didn't make much sense for Fallout 3 to not have any rain and in the mojave it made sense for rain to not appear even though it must happen at some point but in zion we saw normal rain. The area that Fallout 4 is set in is not arid, so rain should occour. And it can't be acid rain every other week as it'd end up killing everything in the region.

Radioactive storms. Envision the northern light effects in skyrim, but as fog banks moving along the ground set to the sound track from Fallout One and "The glow'. . Your Pip Boy geiger goes crazy and you need to head for cover immediately cause either your skin starts steaming or you begin to stew in your metal armor.....

I hope there is a good weather system in 4, one thing NV lacked imo, storms and snow would be a nice feature.