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: white, shades of gray, greenish-black, fluffy, puffy, full and thick, feathery, wispy and thin, scant, covering the whole sky, obscuring the sun/moon/stars, fast-moving, drifting, roiling
Touch: wet, damp, misty
Mood: Different kinds of clouds can create different moods. Many people associate white fluffy clouds with happy memories. They can evoke feelings of contentment, joy, and optimism. Quick-moving clouds, usually accompanied by wind, can bring about a feeling that change may be coming. Dark, heavy thunderheads can create an ominous mood and heighten anxiety or fear. On the other hand, rainclouds can also bring about relief and excitement in an area that has been oppressed by heat or drought. Prolonged overcast skies can evoke feelings of oppression, irritability, and even depression.
Symbolism: foreshadowing of ominous events to come, hiding or revealing information, oppression, light-heartedness, innocence
Possible Cliches: mother and child laying in the grass and finding pictures in the clouds, clouds parting to let the sun shine on a happy occasion or event, dark clouds and thunderclaps that herald a villain's appearance, an overcast day that accompanies a character's gloomy mood
Other: Here is a website for kids that discusses with simple explanations and pictures the different kinds of clouds, where they form, what they look like, and what they represent in the weather world.
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.