Think about the film Fargo and the series based on it. It’s set in North Dakota, where winter is long and dreary and snowy. People go about their days regardless of the snow; they’re used to it. But it does affect how they look, act, and what they wear.
Climate can provide transitions. In The Wonderful Wizard of Oz, a tornado whisks Dorothy away from a dreary grey farm to a colorful fantasy land. If your story is set on the coast of Cornwall, the weather will affect the population’s business interests. A wild storm can wreck fishing boats, destroy buildings, and wash characters into the sea to a watery grave.
The weather can even affect the way people act. The Bureau of Justice Statistics did a study on how climate affects crime rates. Some types of crime rise in the warmer months, and others peak during autumn. Anyone who’s lived through a heat wave knows how crabby scorching summer days can make you feel.
If your story includes a crime, climactic events can hinder or help the perpetrator or your protagonist as he tries to solve it or even becomes the victim. Someone fleeing in the snow leaves footprints. An ongoing blizzard erases them. Rain washes away evidence, or exposes it. An attempt to pursue someone across the desert becomes a struggle for survival. Phone lines go down in an ice storm and cell towers become unusable.
Stephen King used a storm in two interesting ways. In Storm of the Century, a TV miniseries penned by King, a dangerous blizzard traps the residents of Little Tall Island. An odd, supernatural stranger named Andre Linoge makes them a proposition they quite literally can’t refuse. The storm blocks any egress from the island, so there is no one to help them or interfere with Linoge’s agenda.
The Wind through the Keyhole is the eighth Dark Tower novel. It takes place after the events in Wizard and Glass (Book IV) but before The Wolves of the Calla (Book V). A huge and powerful storm called a starkblast swoops down on the ka-tet and they must shelter in an abandoned building.
While they hunker down, Roland tells them about an event following the death of his mother, in which he and his friend Jamie were sent to deal with a skin-man (a werewolf in Mid-World). While recounting this story, he gives them another, one he told the traumatized survivor of this monster, a story about another little boy that may, in Mid-World, be either legend or true.
Both stories use weather as a means of confinement. In Storm of the Century, it takes on an extra element of destruction—it almost seems as though Linoge is an extension of the storm itself. He arrives with it, he takes what he wants (much as a tornado eats everything in its path), and leaves with it. The starkblast in Wind through the Keyhole also leaves massive damage in its wake, but it functions mostly as a reason for Roland to spin his tales. King did not publish it until 2012, eight years after the series had ostensibly concluded with Book VIII. It allowed him to shoehorn a couple more Mid-World stories in, and it nicely settles the psychological dust following the emotionally harrowing memories of Wizard and Glass.
Besides plot points, you can use the changes in weather to reflect the mood of your story. A brassy, hot summer can feel either playful or desperate, depending on what’s going on. Spring and autumn tend to produce unsettled weather—warm and bright one day, dark and chilly the next. The quality of late afternoon sunlight shifts in autumn. One can feel the clamp of darkness looming. Shorter days feel like the end of something. If your characters are facing the conclusion of their personal business, it might make sense to set the story in autumn.
Or you could contrast it to unsettle them and the readers. Imagine two characters, Alec and Henry, in a relationship. Alec abandons Henry right at the start of tourist season, leaving Henry to manage their seaside restaurant on the pier alone. In happier times, the approach of summer excited Henry, a shiny coin of promise both for their economic stability and their social life.
Now, the summer is stark, hot, ugly, and unpleasant. The heat and sun don’t invigorate Henry; all he wants is to crawl into bed in the clapboard beach house he shared with Alec and cry until his eyes fall out. But he has to run the restaurant—without that income, he would have to sell the beach house and move far from the coast he loves. In this way, the mood of the setting conflicts with the character’s mood. Your reader can feel Henry’s irritation and frustration with the season he formerly loved.
As I mentioned in the T post, incorporating changes in climate marks the passage of time. These are only some of the ways you can use weather in your setting to color your story. Experiment a little and see if it makes a difference.