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: kids playing outside, sprinklers on, people wearing tank tops/shorts/flip-flops, crowded pools and beaches, people fanning themselves, panting dogs, heat waves rising off the concrete, sunny days with intermittent showers and thunderstorms, lush green plants, fireflies blinking, bats dipping and flitting at dusk, tall grass, lawns being cut, fire hydrants gushing, bonfires and sleep-away camp
Smell: meat grilling on the bbq, sunscreen, bug spray, sweat, chlorine, rain, fresh-cut grass
Taste: sweat, sunscreen, salt water, ice cream, watermelon, popsicles, beer and soda, lemonade
Touch: sting of mosquitoes, sweat trickling down your face, clothes that stick to you, sunburn, too-hot asphalt, breezes that are warm and cloying, the shock of cold as you jump into a pool, the heat of the sun beating down on you, hot air rushing in as you open the door
Sound: the whir of oscillating and overhead fans, a/c humming, children laughing/running/squealing, thunder, falling rain, water splashing at the pool, fireworks booming, mosquitoes buzzing, lawnmower noise
Mood: Many peoples' memories of summer revolve around summer vacation, picnics, barbecues, and staying up late. Summer evokes happiness and nostalgia and memories of carefree childhood.
Symbolism: childhood, innocence, freedom. If using the seasons to represent the stages of life, summer can also symbolize maturity and adulthood.
Possible Cliches: ?
OTHER: As always when discussing the weather, the length and severity of summer vary by region. Also keep in mind that the cues from your childhood may no longer be common today, or may be confined to smaller, specific areas. Squeaking screen doors and open windows were summer fixtures from my past. But with changing times, more people have a/c, so unless your character lives in a less temperate region, these cues are now the exception rather than the norm.
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.