Lightning is caused by the discharge of electricity between clouds or between clouds and the earth. In a thunderstorm there is a rapid gathering of particles of moisture into clouds and forming of large drops of rain. This gathers with it electric potential until the surface of the cloud (or the enlarged water particles) is insufficient to carry the charge, and a discharge takes place, producing a brilliant flash of light.
The power of the electrical charge and intense heat associated with lightning can electrocute on contact, split trees, ignite fires, and cause electrical failures. Most lightning casualties occur in the summer months, during the afternoon and early evening. An average of 215 structural and non-structural fires are caused by lightning each year in Minnesota, with average annual damages totaling $3,013,171 dollars.
Lightning causes an average of 35 wildfires per year in Minnesota, with average annual suppression costs totaling $54,864 dollars and average annual damages totaling $10,357 dollars based upon statistics maintained by the Minnesota Department of Natural Resources (MN DNR) Division of Forestry. Wildfires caused by lightning are a concern for St. Louis County.
Lightning during thunderstorms has impacted residents of St. Louis County. In 1970 power was lost in most of St. Louis County as a result of strong thunderstorms moving through the area. In 1995 the Iron Range communities lost power as a result of lightning during strong thunderstorms. According to data from the National Climate Center, there were 11 lightning events reported between 1994 and 2001 resulting in six injuries and $1,000,000 dollars in damages. The most common impact in St. Louis County is wildfires and structural fires caused by lightning and damage to electronics as a result of power surges.