Focus on the physical setting of the story (the location of the house and the storm) and discuss their impact on Calixta's and Alcee's actions.
Calixta and Bobinot's house sits in open field with a "low shingled roof" and "many tall trees standing about." At the edges of the open field are more trees and scattered about are other buildings and "far off cabins" still in view.
The storm approaches from the west, a "cyclone" the likes of which haven't been seen in "two years time." As the storm descends upon the house, the windows become clouded with condensation and the heat and humidity become stifling. Lightning strikes one of the trees at the edge of the field and the rains become heavily enough to obscure the view of the cabins and anything beyond the house itself. It is almost as though the world is closing in on Claxita and Alcee. The outside world--and certainly the responsibilities each feels toward their respective spouses and children--melts away as does their view beyond the house. Their only concern and their only focus at that point is the lust they feel for one another. Even the storm itself and the "roar" of its "crashing torrents" are ignored as they "swoon together at the borderland of life's mystery," enjoying their "quivering ecstasy."