This is a nice little rhyme, though it's hard to be sure of whether it will be good for the novel without having read it, or knowing the synopsis of the plot/story. Though, within the poem itself is a small story of weather which I quite like.
I prefer the second version without the line break. With it being such a short rhyme, with it's a,a,b,b scheme I don't think the caesura it creates brings anything to the poem. Though I can see why you would want to put the pause in there, i personally think it's better without.
I love the imagery, it's everything about a summer storm condensed into two rhymes, without saying too much, or getting too far into talking about the weather, which as a metaphor can be a little cliche and over-done.
Punctuation and Grammar.
I wonder about the use of doth, it's hard to know the background of the choice of word in such a short poem to be placed at the beginning of a novel. Perhaps I'm analysing it too much, but if it's language used in the novel then it'll fit in fine. I usually like punctuation, but this looks so clean without it.
I nice little rhyme that would do well at the beginning of your novel.
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