Weather affects people in significant ways. In the spring, we tend to have weeks and weeks of non-stop wind and this makes people really irritable. Tempers fray and patience becomes limited. In the summer, long periods of sunshine and warm temperatures make people happy and mellow. Winter, with long, cold, dreary spells is always a time for depression and despair.
Weather can be used in your writing as more than just an element of setting. In movies a shot of a storm brewing on the horizon is often a visual cue that something dramatic is about to occur. I don't suggest you are that obvious in your writing, but using the weather can create another layer of texture and meaning in your work.
In my novella, Angels, Oddities and Orthodox Habits, the action takes place in a small town during a long, hot summer. The unrelenting sun takes its toll on the inhabitants of this little village and bad things start to happen, cracks appear in the fabric of society. Only once the truth behind the horrific events has been exposed, does the rain finally come. And when it does, it is the perfect background for the climactic scene between the two protagonists. Not only does the rain provide a dramatic setting for the finale, it suggests a cleansing of the earth, of the scene, while the thunder and lightning crashing overhead echo the fight happening between River and her brother, Salvation.
How do you use weather in your work?