Can meteor swarm trigger in the air?

Question

The wording of METEOR SWARM, a 9th level spell, starts with:

Blazing orbs of fire plummet to the ground at four different points you can see within range. Each creature in a 40-foot-radius sphere centered on each point you choose must make a Dexterity saving throw. The sphere spreads around corners.

When my monster cast this on the group, there was a bit of confusion due to the wording of the spell. A player pointed out that because of the phrase "plummet to the ground," the meteors must impact the ground. That being the case, any creature that is flying above 40 ft would be outside of the range of the spell. Is this the intention of the spell?

While this at first seemed plausible, I ruled that due to the phrase "sphere centered on each point you choose," I could choose to have the meteors explode at any point in the air, making flying creatures reachable targets.

Another point is that spells that explicitly limit their area effect to the ground tend to say so unambiguously. Examples include:

EVARD'S BLACK TENTACLES

Squirming, ebony tentacles fill a 20 foot square on ground that you can see within range.

SPIKE GROWTH

The ground in a 20 ft radius centered on a point within range twists and sprouts hard spikes and thorns.

Also, the spell specifies that it is a sphere, and limiting it to the ground would necessarily limit the spell to a hemispherical range.

Lastly, it's a 9th level spell. By 17th level, most PCs can fly, and aerial battles are common. It doesn't seem likely to me that the intent of the spell was to limit it to the ground. And of course there's also this: https://en.m.wikipedia.org/wiki/Chelyabinsk_meteor

Answer 1

It explodes on the ground affecting creatures in the air; the DM may adjudicate it differently

To me it seems pretty clear that the points on the ground are the points you chose. The text says:

Blazing orbs of fire plummet to the ground at four different points you can see within range. Each creature in a 40-foot-radius sphere centered on each point you choose must make a Dexterity saving throw. The sphere spreads around corners.

The four points you can see must be on the ground. Writing "plummet to the ground at four different points on the ground that you can see" would just be redundant (and a bit silly). And it should be clear from context that the points you chose are those four points you see. Why would the spell text talk about these points in the first place, if they weren't? Or why would the text even mention the ground, if you can shoot the flaming orbs to hit just anywhere?

Once they explode there, they will do so with a sphere radius of 40 feet. Anyone in that radius will be caught in the blast, wether on the ground or flying above ground.

So far for rules as written. As for rulings, I could see a DM adjudicating that someone in the path of these burning meteors and getting hit by them will cause them to explode too, and allow to pick points in the air where flying creatures like airships or a dragon can serve as the point of impact in place of the ground.

As a historical note: the original version of this spell in AD&D 1e did not have this limitation of "on the ground". It explicitly shot out from the caster, affected everyone in the path, and then exploded at a given distance, much like fireball. DMs who like to consider the game's history for context in their rulings might take this as an additional point of support in ignoring the restriction and just picking any points in range.

Answer 2

It’s not entirely clear from the wording but I’d say yes, they can trigger in the air

“Plummet to the ground” implies that the meteors come into existence somewhere high above the ground and then fall down until they reach the ground. But then the spell says

(…)40-foot-radius sphere centered on each point you choose (…)

It doesn’t specify “each point you choose on the ground” like some other spells do where the effect explicitly takes part on the ground, e.g. Everard’d Black Tentacles.

I’d say that having the meteors explode in the air is in line with the wording of the spell - the meteor does plummet to the ground but explodes before reaching it. As it doesn’t specify that you must choose points on the ground, in my opinion this is perfectly fine by RAW.

Answer 3

RAW : the orbs of fire explode on the ground

The spell states the following :

Blazing orbs of fire plummet to the ground at four different points you can see within range.

Nothing else in the spell mentions anything about the orbs themselves. As written, they do not act as projectiles or anything of the sort, and thus wouldn't interact with anything on their path.

As written, if anything, those orbs are purely decorative and would happily phase through any obstacle that may be between them and their destination. Of course, the DM is free to houserule otherwise, depending on the situation.

The tricky part is the interpretation of what "four different points you can see within range" means. The key here is the part right before :

Blazing orbs of fire plummet to the ground at four different points...

Just to make extra sure, I checked the english definition of "to plummet" (not being a native english speaker, better safe than sorry) and it does seem to implicitely indicate a downwards movement.

The way I understand how this sentence is built is that "at four different points" is a precision on the previous "to the ground" part. What I mean by that is that it gives a more precise description of the part of the ground towards which the orbs plummet.

Because of that, those points cannot be anything else but the points towards which the orbs plummet, and thus they have to be on the ground.

As to what "the ground" may exactly be defined as, and how it could lead to some... interesting interpretations, I redirect you to this question.