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: Blindingly white jags that fork and branch off of the main strike. Lightning can travel from the earth to the clouds, from clouds to the earth, or from cloud to cloud. Lighting strikes may occur singularly, with many seconds or minutes between them, or they may occur seemingly continuously for a period of time. Lightning may be accompanied by rain, wind, hail, and other storm conditions. It can also occur as what people mistakenly refer to as heat lightning, which flashes from cloud to cloud, makes no sound, and has no additional weather pattern. In reality, this soundless flash of light is actually lightning from a thunderstorm that is too far away for the thunder to be heard.
Smell: rain, an electrical/ozone smell, burning
Touch: The surface of a lightning bolt reaches temperatures hotter than the sun, so a bolt can wreak serious havoc on whatever it hits. People struck by lightning express many different physical sensations, but the common complaint is burns at the entrance and exit points. Electrical burns can lead to a number of other problems: cardiac arrest, internal organ failure, infection, and brain damage, not to mention the injuries sustained when a victim passes out, falls down, or is thrown a great distance.
Sound: Thunder may follow lightning if it is within hearing distance. Other storm sounds may be evident, such as wind, rain, or hail.
Mood: Lightning accompanies storms. As such, it often fills people with a sense of foreboding or impending doom. Lightning is insanely fast, its power and destructive potential beyond our ability to fully understand. It evokes fear, and awe, and the desire to seek safety and shelter.
Symbolism: power, nature, God or fate, punishment, the harbinger of doom, randomness
Possible Cliches: greased lightning, lightning never strikes the same place twice (which apparently isn't true), someone being as fast as lightning, lightning as the forerunner of an alien invasion, 1.21 jigowatts (okay, so that's not a cliche, but I do enjoy saying it in my best Christopher Lloyd voice)
OTHER: Lightning occurs anywhere you have thunderstorms. If a storm is over 12 miles way, you can see the lightning but may not hear the thunder. Roughly 7 out of 10 lightning victims survive, but they're usually left with lifelong health and psychological problems (understandably).
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.