WEATHER is an important element in any setting, providing sensory texture and contributing to the mood the writer wishes to create in a scene. With a deft touch, weather can enhance the character's emotional response to a specific location, it can add conflict, and it can also (lightly) foreshadow coming events.
However, caution must accompany this entry: the weather should not be used as a window into a character's soul. The weather can add invisible pressure for the character, it can layer the SCENE with symbolism, it can carefully hint at the internal landscape, but it must never OVERTLY TELL emotion. Such a heavy-handed approach results in weather cliches and melodrama (a storm raging above a bloody battle, a broken-hearted girl crying in the rain).
Sight: slowly fading light; increasing shadows; what's left of the sunlight shining vibrantly red, orange, or yellow; everything darkening to purples, dark blues, and grays; remaining sunlight shining almost horizontally from the western horizon; swooping bats; fireflies (in rural areas); nature is returned somewhat to its pre-human state as people move indoors
Smell: food grilling on bbq's, bug spray
Touch: a cooling of the air
Sound: crickets and other night bugs begin chirping, frogs croak, outdoor 'people' sounds fade away (kids laughing, doors slamming, voices, music), distant sounds grow louder in the silence (dogs barking, cars starting)
Mood: Dusk is the sign that the day is ending. It brings about a feeling of relief as the stresses of daily life begin the turn toward rest and relaxation. Many people feel calm and peaceful at this time of day. The weather at dusk, as at any time of day, helps to influence mood. A rainy, windy dusk may cause nervousness and apprehension as the stormy day turns to stormy darkness. Breezy, airy dusks may lift the spirits. And context, as always, is key. Dusk in many supernatural settings brings about a totally different atmosphere of fear, danger, and impending doom.
Symbolism: endings, transition, decline of life, fading away
Possible Cliches: use of dusk to signify a dying person's descent towards death
OTHER: Clean air usually generates orange and reddish light at dusk. When the air is hazy or dusty, the color is subdued to yellows and pinks. Also, though the terms 'twilight' and 'dusk' are often used interchangeable, many sources site dusk as being the latter, darker part of the twilight period that comes between day and night.
Don't be afraid to use the weather to add contrast. Unusual pairings, especially when drawing attention to the Character's emotions, is a powerful trigger for tension. Consider how the bleak mood of a character is even more noticeable as morning sunlight dances across the crystals of fresh snow on the walk to work. Or how the feeling of betrayal is so much more poignant on a hot summer day. Likewise, success or joy can be hampered by a cutting wind or drizzling sleet, foreshadowing conflict to come.