I don't know if there's some technical term used by meteorologists, but I think I'd instinctively say a "group" of clouds unless something more poetic was called for.
Remember it is OK to use plain, easily understood words when the fancy ones don't buy you anything. This reminds me of the pointless list of rarely used collective nouns for animals that some people think it's vitally important to their well-being to memorise.
Consider brief,
précis,
survey,
overview,
conspectus,
digest,
compilation,
compendium,
collation,
corpus. A brief, for example, is "An attorney's legal argument in written form..." but formerly was also used as "A summary, précis or epitome; an abridgement or abstract", which all are forms of collections of facts. Collation is a surprisingly versatile word, the relevant meaning here being "A collection, a gathering" rather than "5. Any light meal or snack" or more-specialized "2. The Collationes Patrum ...", "3. A reading held from the work mentioned above...", and "4. The light meal taken by monks after the reading service mentioned above". For survey the relevant meaning is "A particular view; an examination ... of all the parts or particulars of a thing", which is how it is used in the phrase survey article, "... a paper that is a work of synthesis, ... a survey or summary of a field".
Update 1 I disagree in general with the comment
Each of the above defines the way the facts have been compiled, the nature of the source, or something qualifie[d]. None of them seems to be an unqualified substitute for 'a collection of facts'. – Kris
but will address it only for compendium. Wiktionary shows "1. A short, complete summary; an abstract" and "2. A list or collection of various items". To a question like "Have you got anything about it?", one could reasonably reply either of
Here is a compendium of facts for you to look at.
Here is a compendium for you to look at.
but in the former "of facts" seems redundant.
Note, compendious is an adjective for which Wiktionary shows "1. containing a subset..., succinctly described; abridged and summarized" and "2. briefly describing a body of knowledge". Certainly the latter sense is appropriate for "collection of facts". On the other hand, the definition and synonyms of it inject a qualification of brevity.
Best Answer
I believe you are asking for a collective noun, and for fire there isn't one. You could have a "wall of fire" or "blaze of fire". What are you trying to achieve by using a collective noun here?
If there's something in particular you're trying to describe, consider a synonym: pyre, flame, conflagration and so on. Keep in mind that a construction like "pyre of fire" would be considered a pleonasm.
Based upon your edit, the nature of the question is totally different. In this case, why not go with several (your first inclination), series as Jim suggests, or any number of synonyms: