Those thunderstorms do more than change your afternoon plans - they cause a lot of damage. A bolt of lightning can cause injury or death, fire, and destruction of electric-powered equipment.
Lightning is electricity, and electricity is always looking for the fastest way to reach the earth.
Water, metal, trees, or even people can serve as a conductor to provide that path to ground. When a thunderstorm threatens, you should get inside. Even though the thunderstorm may not be directly overhead, lightning can strike several miles from the parent cloud. Hilltops, hillsides, and buildings surrounded by flat fields all tend to attract lightening. A wooden rain shelter or stand of trees doesn't provide adequate protection.