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: sun showers, longer days, trees and grasses greening up, flowers blooming, buttercups, daffodils, tulips, lilies, dormant plants pushing back up through the earth, buds and blossoms on trees, increased animal activity, baby animal sightings, effects from breezes, warm weather clothes, rivers rise and run swiftly from snowmelt, more butterflies/bees/other insects (because of increased blossoms), people working in their yards, birds flying north, nest-building, the emergence of hibernating animals, plants pushing up through snow or ice, increased pollen in the air, umbrellas and rain boots, kids playing baseball, rainbows, cherry blossoms
Smell: the clean damp smell after it rains, newly turned dirt for gardens, floral scents
Taste: rain, Easter candy
Touch: the sun's warmth on your skin, the fresh touch of the breeze as opposed to the frigid one you've felt all winter long, spongy or grainy feel of dirt in the garden, dirt clods falling on your feet as you pull weeds, the clean feel of the air on your legs and arms after so much time wearing long sleeves and pants, allergy symptoms
Sound: rushing water, rain falling, bare feet slapping the pavement, puddle-splashing, birds chirping, insects buzzing, kids-playing-outside sounds, the honk of geese as they return home, the crack of balls hitting bats
Mood: After so many months of cold weather and brown landscapes, spring brings a renewed sense of optimism. Spirits lift, people are more friendly and kind. Spring evokes hope and renewed vigor.
Symbolism: renewal, rebirth, beginnings, second chances, cleansing
Possible Cliches: spring chickens, April showers bring May flowers, robin's egg blue
OTHER: As always, weather and seasons vary by region. Spring in Canada looks very different from spring in southern California. Temperate areas may have a very short spring, if any at all.
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.