two female figures of the story.

From the moment we first meet her, Calixta is linked to a form of female sexuality. In a moment of foreshadowing that deepens the connection between the storm and sexuality, we learn that although Calixta “did not notice that approaching storm,” “she felt very warm and often stopped to mop her face on which the perspiration gathered in beads.” Moments later, her ex-lover, Alcée, appears at the door. 

The language used to describe the conditions produced by the storm is sensual in nature. We learn that it is “stifling hot,” and when a nearby bolt of lightning strikes, the language is particularly sexual:

Calixta put her hands to her eyes, and with a cry, staggered backward. Alcée's arm encircled her, and for an instant he drew her close and spasmodically to him.

Perhaps ironically, Calixta’s newly discovered sexuality does not seem to threaten her identity as a wife or a mother. In fact, it seems to strengthen it, as we learn that she is more patient with her family upon their return.

Conversely, the storm provides Clarisse with the power to escape from her sexual identity as Alcée’s wife. Although this movement is the opposite of Calixta’s in that Clarisse uses the storm to vacate her sexuality, the end result is the same. We learn that, in so doing, Clarisse is able to “restore the pleasant liberty of her maiden days.” For these two characters, the storm functions as a symbol of sexuality that achieves very similar ends through opposite means.

"The Storm" speaks to the belief that surrendering to passion need not have disastrous consequences, despite what conventional morality suggests.  The tryst that Calixta and Alce indulge in is consensual, and their passion is unrestrained.  As her character is introduced, Calixta is completely immersed in her sewing—so much so, in fact, that she doesn't notice the approaching storm. She is perspiring, her gown loosened and "her yellow hair, disheveled by the wind and rain, kinked more stubbornly than ever about her ears and temples." She is presented as entirely natural and engaged in life, which makes her spontaneous lovemaking with Alce seem in keeping with her character.  When their passion is spent and they move to return to their lives, Alce "turned and smiled at her with a beaming face; and she lifted her pretty chin in the air and laughed aloud." Neither of them are wracked with guilt, and they do not make promises to one another or express regret.

When Bobint and Bibi return home, Calixta greets them lovingly and effusively.  She is as "in the moment" with them as she had been with her sewing and her tryst with Alce. Whether she is in the domestic sphere or elsewhere, she is passionate, authentic and natural.

Alce composes a loving letter to his vacationing wife, Clarisse, that tells her she can stay away as long as she likes and that "health and pleasure were the first things to be considered." Clarisse's reaction is that "the first free breath since her marriage seemed to restore the pleasant liberty of her maiden days."

"The Storm" focuses on Calixta and Clarisse and condones their pursuit of pleasure in whatever form it takes. Though Alce enjoys the same freedoms, as a man, Chopin implies that they were never in question. The theme is decidedly feminist in that each woman values self-liberation to pursue her passion without the burden of guilt imposed by societal expectations for women.

One possible theme is finding happiness and fulfillment through unconventional means.  The main character is a woman who finds incredible gratification in an elicit affair with an old acquaintance.  Chopin seems to be indicating that freedom and happiness can be found outside of regular moral conventions of the time.  Calixta, who commits the affair, seems perfectly happy, rejoicing, and almost giddy afterwards, treating her husband and son with unusual kindness and levity.  So, even though Calixta seemed to love her husband, and had a husband who, by all outward signs, loved his wife, she still found even more fulfillment through satisfying her sexual desires with another man.  Chopin's stories often have this theme of women finding happiness in unconventional ways; take "The Story of an Hour" for example, where the main character, a housewife, is ecstatically happy at the freedom that her husband's death gives her.  This theme is seen through "The Storm" as a woman, after surrendering to an affair-which was scandalous and wrong in her society-actually seemed to gain quite a bit of happiness from it.

In Chopin's "The Storm," the fulfillment of passion and desire has a cleansing effect like that of rain on the marriages of the adulterers. 

Alcee and Calixta, with a history of sexual encounter, find their passion reawakened when Calixta, scared by the storm, reacts by moving into Alcee's arms.  The sexual descriptions would have been controversial enough in Chopin's day, but the approval the story grants to the encounter even more so.

Instead of her usual grouchiness and condemnation when her husband and son enter the house after walking through the aftermath of the storm, Calixta is welcoming and warm, fulfilled by her passion.  Alcee, too, is loving to his wife, and tells her to stay away on her vacation for longer than planned if she'd like to.

Alcee's wife, too, finds marriage confining, and her vacation from her husband is welcome for her, too. 

The story suggests that not only is adultery not harmful, but it is liberating and cleansing, and even necessary for a succesful marriage.  The brief adultery is harmless, and even helpful.

In my opinion, the theme of this story is sexual liberation and freedom.  Specifically, I think that Chopin is saying that people should do what they want to sexually -- they should do what feels good rather than sticking to what society tells them it is alright to do.

I think you can see this because of a couple of things.

1. Neither Alcee nor Calixta is unhappy with marriage in general or with their own marriage.  So it is not a story about hating marriage as an institution.
2. Nothing bad happens to either of them as a result of their infidelity.  So it is not a story that is meant to teach conventional sexual morality.

Instead, it seems that the point of the story is that this fling during the storm was satisfying for both of them and that that was a good thing.